Lee, your posts look pretty good to me!

I have worked with all of the currently availabe naturally aspirated .91 FS engines. I have flown the 4*60 with a Saito .91 and it flew really well but was not a fast model. It has a huge wing area for its weight such that a couple of ounces variation in engine weight and consequent CoG balancing is materially insignificant as far as the airframe's performance is concerned.

The most powerful engine of all the .91 naturally aspirated engines running heavier props (13x9, 13x10 and 14x8 for example) is the OS .91 Surpass. It handily outpulls a Saito .91, TT .91 and Magnum .91 running an APC 13x10 by at least 300 rpm (9200 versus 8800 to 8900). I have compared these engines on the same fuel, same day and same prop and this result has been consistent.

When you lighten the load some, the TT .91 becomes quite competitive. It will swing a 13x8 around 10.000 rpm, pretty much equalling the OS .91 and outperforming the Saito .91. The TT .91 I see most often (a club mate's) is an absolute honey of an engine with good power and an amazingly reliable idle. I can't vouch for consistency with the TT, as I have not seen many examples. The OS .91, Saito .91 and Saito 100 examples I've worked with, as you'd expect with Japanese engineering, have all been very consistent.

The Saito 100 pulls heavy lumber (14x8, 15x6) a little better than the .91s but becomes a little breathless at and above the high nines in my experience. The Saito 100 is quite expensive ($280 odd), which makes one wonder if an additional $50 odd is worth the stretch to buy a YS 1.10, which is much more powerful than any of the aforementioned engines.