Hi again All,
And thanks for the detailed info. Flybert - this clears things up considerably. I've got the ReDux files in the simpatch folder of a stock copy of RB3D. Noticed that it's slightly less twitchy in MMP than SP - probably because it was intended for MMP as you say.
More impressions after further testing of the ReDux patch in SP in RB3D on an Intel Mac: planes are more torquey/twitchy than in the Greybeard FM for sure.
The German planes: easiest to fly are the Alb. D.2, 3, and 5; the Alb. D.2 is particularly good against various Nieuport types, but has an abysmally poor climb rate; the D.5 is a better climber but has a tendency to slip into a spin on tighter turns; the Halberstadt is very entertaining and manageable, as are the Pfalz D.III and XII (the D.XII is particularly good against the Sopwith Snipe); the Pfalzes, although prone to some spinning, don't break that often; didn't test the Fokkers since I don't fly them anyway.
The Allied planes: easiest to fly, for me, are the Tripe and Nieuports (the Tripe doesn't break as easily as the Nieuports however and is my favorite of the Allied fighters after ReDux is applied); the Camel and Snipe are stronger than the Tripe but have a much greater tendency to spin than their counterparts in the Greybeard FM; didn't test the SE5a and SPADs since I don't fly them; also didn't test early fighters like the Bullet and DH2 but noticed generally that the monoplanes are also more prone to spinning than in the Greybeard FM.
Verdict: will most likely stick with the Greybeard FM for SP, and leave ReDux for MMP only.
Added note: will try to record a clip of ReDux in stock SP and will upload it to my YouTube channel in the next few days; after that will further test the old "Royce II" FM (still available on the HASP website) for stock RB3D (tried the Royce II FM just now and it doesn't look too bad; feels half-way between the Greybeard and ReDux FMs in terms of twitchiness).