It should work. Im currently making a smp private pack based off of ultimate, im currently up to 200 mods and it's stable (besides already known bugs from mods), and I have divine rpg working fine. I will post my configs once it's all finalized so that anyone can add any of those mods without any conflicts as I've not modified any of the default FTB config IDs. I have disabled secret rooms bc it causes mystcraft to crash and also voxel map bc I hate it. The only FTB config that gets modified is mystcraft provider id setting otherwise all your mystcraft ages tend to lead to divine rpg worlds.
If more mods that add creatures would let you edit the entity IDs it would be even better but they don't seem to. Mo'creatures works with my pack but I have it disabled bc it Jacks up spawning even with other mods controlling it. I've pretty much taken any stable smp mod that's not blatantly OP and plugged it in and resolved all conflicts. I still have several more to add though.
What mods are you using?