Hi
I'm a local pilot. Mull is in superb condition just now. Leeds-Prestwick-Mull is ideal in good weather conditions. Couple of 'escape routes' for poor weather require local knowledge (Crinan canal/Loch Fyne gets you from west coast south of Oban to open water east of Arran, or vice-versa) and further south to West Loch Tarbert/Tarbert will bring you out at roughly the same place just north of Arran. Or you could follow the west coast all the way to Machrihanish, giving you the option of Gigha.
As a one-time Warrior pilot I'd be extremely careful about take off performance 4-up out of Mull, particularly taking off to the west, where a right turn after departure is advised due to a bit of high ground. If it can be done I'll bet it's with a light fuel load but Avgas, tea and Jammie Dodgers are available at Oban.
If you're looking at a chart and considering places like Colonsay, Coll or Jura, then forget it in a Warrior. Gigha is not as good as Mull, a bit rough but reasonably well maintained, but it's got a substantial part of its length (1/4 to 1/3 perhaps) that is uphill.
There's a Warrior at Glasgow Flying Club that was into Mull just the other day. Maybe those guys will see this post and give you a better idea of what a 4-up Warrior might be like. Or try the club on 0141-889 4565 and ask to speak to a local pilot - Mull is a regular and popular destination for the GFC Warrior.
Good luck and enjoy!