I too am a big fan of Saitos I own and operate over 10 of them.

One thing I notice however, is that in the larger sizes starting with the 125 is that the spool up is NOT as quick as with the smaller ones no matter how they're tuned or which prop is used.

I have two 100's and both of them make my 5-6 lb planes JUMP out of a hover with a 15x6 wood prop (doesn't matter which brand).

I have a 125 on a 7.25 lb OMP Fusion, as do 3 other guys in my club, and we all see a lack of "jumping" with the 16x6 props we use. The pull is strong in all flight regimes and the plane pulls through everything in nice pattern type style, but the "hyper" throttle sensitivity just isn't there and I think that's what your'e seeing. The 150, 120, and 180 also exhibit this lackluster spool up property. Once you get them moving they're fine and have lots of grunt, but off the line they aren't as good as say a YS 110 is with it's pressurized carb system.

My 72's and 82's and 100's are super in that regard, but I think the 100 is the last of the breed when it comes to spool up. I have yet to see the new 115 so I'm curious to see on which side of the fence it lies.