I've only ever played through Skal once and I had a really good time to be honest! I personally left at level 20, if memory serves me right, and by that time my character was definitely someone who was well known by others, which was a bit crazy given I had only been there a week or two.
Another post above is correct in that the faster-paced nature of Skal is very refreshing since there aren't factions or groups or even 'deeds' that are around/known RL YEARS after the fact, however I'd also counter to say some of those on the main island aren't known in a good light for maybe one misdeed, and others worked very hard to be well known for the evil-doer or do-gooder that they are. Part of what endears me to Arelith proper is it's very rich history of the characters who come across and leave their mark. Not only do we have D&D lore, but we have Arelith-specific lore because of the tendency to hold onto things like that. So I'd disagree with merging Skal with Arelith, making it it's own non-leaveable server, or deleting it entirely, since while the history isn't really there because it's so rapid-moving, the ability to play through it and become 'someone' for a short period of time is a very refreshing thing to do from time to time. Just a nice change of pace every so often.
As far as Epics staying and maintaining their time on Skal, I agree with this change. If you go past 19, you get shoo'd. It's become an IC joke in some circles that people from Skal who come to the main settlements were 'Big fishes in a little pond' based on how they act since they were hard-hitters and well known on Skal, but are now essentially a nobody who is trying to bullrush or build their way back to their previous status in Arelith proper. It can be quite daunting of a transition for those characters since they basically have to 'restart' their journey. Granted this could be a personality trait of their character and that is absolutely fine, however if they would prefer to stay that well-known staple, it's probably best they stay in Skal at level 19 because RP ticks can definitely get you into epics even if you're not actively grinding, and it keeps that level of fairness across the other new players. If you want to be a well known and respected (or perhaps hated) person off the bat in say, Cordor, another starting location, you ARE being thrown into social circles that've already been established. It's harder, but doable, but no matter where you start you are more likely to become known by the people in that location since you're putting in that time and effort on getting to know people and access materials and gear and writ-teams and so forth that are quite necessary.
All that is to say, especially when it's being a PvP-centric or conflict aimed character, it boils down to what the player wants to do with their story. They wanna be well known or that big fish? It comes to the choice of doing it once, or having to do it twice. Once in Skal, then again elsewhere. But where-ever they DO go, it's generally recommended that their ability and levels is on par with the others in that location. You're not gonna find many epics in Skal to begin with, but throw a rock and you hit an epic-geared 30 anywhere else. Being level 19 in Skal would be 'The Powerhouse' but the others still have a chance against you. This is a wonderful option for those who don't want to play in a epic-reigning server, they can simply stay on Skal and have that pre-epic experience!
Now as far as epic-level folks visiting, or returning. I'm somewhat biased, given I on the rare occasion do visit Skal on my characters and it's usually something like- 'Oh we're returning this person to Skal who left too early because they didn't know any better' or I'm doing something like selling cheap-o jewelry boxes because both my character and I know there's a market for that kind of thing with the newer players and it's helpful. I personally never go to start a fight, or even end a fight, since I understand I am vastly overpowered for that area, but I recognize not everyone is doing that, and someone else may try to start something with my toon without knowing I can squash them with one hit/spell. That's not particularly fun for anyone, neither me nor the other player.
I think being able to visit for very brief periods of time, like a couple RL hours, should be okay. Whether to sell a commodity, just see what it's like, or with this new change perhaps someone who left Skal to venture the main land, but had a close friend who remained level 19 on Skal that they want to see again. Just visiting is a fun time, and the stories we hear from Skal on the main island make it a mysterious and interesting place that many people 'just want to see what it's like'. However, to avoid any abuse of those visitors (since I don't think any of this conversation revolves around those who are just poking their head in and not causing issues), I think there should be harder restrictions ON those epic-leveled folks who visit. I can think of a few ways to curb this but they're probably more nuanced and would need to be kinked out by people smarter than me. Obviously if you stay past a day, the DMs are gonna turn their Eye of Sauron on you with an MoD and that's fine. But as far as an automated system to help them out in the meantime?
1) Temporarily lowering the level of anyone above 19, to 19, or perhaps to 21 since they ARE a max level character and therefore more powerful than those on Skal. This lowering can revert back once they leave the area.
2) Giving a text time-limit warning of how long they are there before they need to leave, much like how a temporary shop/ship gives you a warning on your property being released soon. Overstay that time limit, and you get booted to the Skal Docks on the surface server. Maybe the artificer teleporting device idea would work for that as an IC explanation!
Anyway, just my ramblings. Hope it made sense, I am freshly awake and newly on the coffee drip, so.