Hmmm. I don't know about Broker's for Martinis (I've never used it for that purpose). But I wouldn't think that the proof makes all that much difference, so long as one uses a decent amount of vermouth. Tanqueray, at 94.6 proof, is the standard Martini gin for Pegu Club's Fitty-Fitty -- and I like it at as much as 4:1.
I think the saffron gin would be Cadenhead's Old Raj (packing a whopping 110 proof, I believe).
Good point about the Tanqueray -- that part didn't dawn on me. I think the Broker's is just a bit too strong to make a good martini (for my taste anyway).
And you are right about the Cadenhead... would love to taste it, but not sure I'm ready to put out that kinda cash to find out!