From what I gather from the forum Thunder Tiger .91s are just fine even tho they take some time to break in. They have better power than the Magnum and about as much as Saito. They weigh a bit more but this is an advantage for most warbirds. They cost about $60 less (than Saito) too!!
Having said that, I own a Saito, but will try a TT .91 if the need arises.