Yes Three do still limit roaming to 19GB as we just noticed on holiday in Ireland.I've used these home and abroad for ages now in my iPad and mifi unit and they're absolutely brilliant. That's a really good price for the 24GB sim
One tiny word of caution about using it overseas... in Europe last year I discovered that 3 have a monthly fair usage cap on roaming data. I'd bought a 24GB sim but wasn't allowed to use it all in one month without incurring extra charges, so now I make sure I've always got two sims to switch around. I don't know if they still have this policy though - could be old news now.
I have lost signal on some beaches with 3 but O2 has gone at same places. Not really suffered loss apart from some areas around Newton Stewart. Can’t say it has been a problem really elsewhere though right up to Mallaig and Skye, Highlands and over Dunoon way. I do use a 4g router as well though and that picks up better than out iphonesThe 3 deals look good but their coverage in the Scottish Highlands looks to be practically non-existent. This is pretty much the only are we tour so it is a deal killer for us.
EE seems to work quite well but their deals aren't as good.