Re: D&D 3.5 Gestalt mid to high level
I'd be OK with that, but I might restrict the classes a bit more than that. Rogue could include Bard, Scout, and Spellthief, but I would not do anything with the Oriental classes. I'd consider other skill-based classes, but they should fit something that works within a Thieve's Guild operation.
As far as the cleric thing goes, I'm not sure on loosening up on that one. The whole campaign idea centers around the gods, and how they have changed after the Time of Troubles. The big change is that clerics can no long sacrifice spells to heal (or harm), instead sacrificing spells to a domain. There are enough gods in the Realms to pick and choose something that should appeal to a player/character. Paladins, Druids (who worship nature gods, instead of spirits) and Favored Souls don't get into that aspect. This would include all the various monster races as well. Lizard-men, goblinoids, orcs, etc. I would want to encourage use of Diving Channeling feats.
Yes it would chafe perhaps, but the ideas I would explore, would have to involve a more invested relationship then that of Paladins, Druids, and Favored Souls usually have with their deities. Heck, as I understand the class of Favored Soul, they sometimes don't even realize who they are being favored by!
I would consider loosening the restriction to needing half of the one tree having to be Cleric, giving more room for specialized builds. e.g. At 8th level, you had to have 4 levels of cleric somewhere in your build. Would that improve the likability of the idea?