I've stuck this here because it is after all a change to the game...

bBorderRegionsEnabled.

I would like to turn this off because I think it will be more immersive to not have an invisible barrier, however, are there likely to be any dodgy side effects to turning this off?
I mean I guess it's there for a reason(!)

Cheers!
Mat

Well, eventually you'll run out of Tamriel, but other than than that, no.

Go for it.
There's no ill effects. In fact quite a few mods require it to be turned off.

Oh fair play then, I shall fill my boots in that case.
Thank you!
Mat

Without the "invisible wall" you eventually fall off the edge of the map. You'll find progressive degradation of content once you're out of sight of the borders, as there's no need for trees etc. that can't normally be seen, but this takes quite a trek. Gross features like distant mountains really are there, and you can go to them. There just won't be a lot to see when you get there. On the other hand, you'll find plants you can harvest ingredients from etc. close to the borders, as they're generated for the entire "region", which typically spills over the map boundaries a bit.

Oh, and you'll have to walk/swim all the way, because there aren't any fast travel locations outside the borders. Take care you don't fall down a cliff and get killed. Make a save before you leave the known universe!

Depending on where you decide to cross the border, it may be difficult to return. There are slopes too steep to climb back up in a lot of places.

There are mods that add provinces such as Valenwood and Elsweyr to your map to explore and do quests and such. Search the Nexus.

I know, thanks, Elsweyr is on my list!