RE: 3 or 4 blade broadheads?
I have used 2 & 3 blades for moose, all have worked well. Personally I have found 2 blade cut on impact will produce the best penetration, however blood trail will be smaller than a 3 or 4. Which isn' t a big problem since moose hit well don' t usually go to far to begin with. I have used 125 Gr Magnus, 125 thunder heads & 125 Gr Muzzy 3 blades, all producing down animals with in short order. Any of the 3 and others will do the job, but moose hides are thick and I feel a cut on impact provides some additional insurance for penetration to the boiler room. If you are using carbons, faster bow and want to shoot 100 gr heads, I would probably go with a cut on impact like the magnus in either the 2 blade or the new magnus stinger 4 blade to start. Montec 3 blades look very good and many have posted good results with this head as well.
BTW, I just tried out the 100 gr 4 -blade stingers this weekend and they shoot awesome with carbons, grouping right with my field points. Blades are very sharp right out of the package(noticably sharper than my trusted muzzy' s I must say) I will be triing them on my elk hunt this fall and can' t see why they wouldn' t be an excellent head for all types of game, they are available in 125 as well.
Oh yeah, do yourself a favour and check out 5 shot site, he knows his BH' s and will answer any questions you may have in regards to a particular head and design.
Good Luck