If I were to do it all over again I would go with a Saito .91 (2oz lighter than 100 and very little power difference).
You are mistaken.
The performance of the 100 over the 91 is staggering. I own 2 91's and 2 100's
The 100 comes in at 550 grams, the 91 at 520, that is only 1 oz.
The difference in static thrust on a 100 vs 91 is near 2 lbs!!!!
The 100 also will turn a 16" prop, put a 16" on a 91 and you will lose throttle response.
if you are worried about the extra oz use CF gear !