I use the 45 APO and also have a Rodagon APO 50 N. At 8X10 and larger, I can see the difference with these and their counterpart Comp S and Rodagon 50..... Frankly, I can't see the difference between the two APO's. As mentioned, alignment issues become critical at these magnifications/open apertures and will likely account for more image degradation than subtle lens variations. If my 45 has a sweet spot, mine shows ƒ6.3 (also a decent compromise for exposure times and some depth of field forgiveness and edge sharpness) and the Rodagon is similar. I very seldom go so large with 35mm as you are dealing with and do 35 work on a 23CII with dichro head and have not had light fall-off trouble with this combo. I gave in to a Versalab a few years back and this has made everything so easy and accurate to keep tuned correctly. I would encourage considering one and wish someone would have prodded me a bit earlier in my darkroom escapades.