Well... let me tell you a bit about results of todays session.
But first, about restrictions. I am not a big fan of multiclassing or mixing prestige classes to draw some ridiculously strong combinations, so you can imagine how sceptic i was about gestalt characters. I completely banned multiclassing (because i don't even know how to calculate xp penalty and when does it apply on a gestalt character) and restricted prestige classes to one per character. Of course, every prestige class has to be revised by me in advance and given a green light, because some are obviously incompatible with gestalt characters. I gave players 4th level or equivalent as starting point, while strongly discouraging LA (max +2) and pointing out that LA is not a good choice in gestalt campaign (some just dont listen). They also got 5000gp starting gold and 5d6 for ability scores.
So, I took a module "Eye of the sun" and used it for few ideas, but after some time my imagination just picked up the pace and I set up a somewhat different twist to the story. Party consists of Human/Cleric-Warmage, Wood Elf/Cleric-Fighter and Air Genasi/Figher-Rogue. Strong rain took PCs off guard, completely unprepared - and even though they were in the jungle at that point, and somewhat shielded from the rain, they insisted on finding a shelter. I ask for Survival check and Air Genasi/Figher-Rogue gets 25. Great, i say, after some time you find a small cave, entrance about 10 feet wide (mind you, "jungle" they were in is located somewhat south of Waterdeep and its called Trollbark Forest

). Time for first encounter... after wandering inside the cave, PCs are soon confronted (and chased back outside) by a... troll! Fight lasted no more than a minute, human was down and bleeding but they downed and burned the troll. Healing time! Wands of CLW in action, everyone is up and running in no time. Wandering deeper into the cave, another troll comes along... killing Air Genasi.
Do you think CR 5 is too much for such party?