That's interesting. I know you can use Kodak RA4 developer without the starter at room temperature, but also read some difference of opinion here with some saying Kodak paper worked well with this and Fuji not as well - I believe you have good results with Fuji CA? More important is the question of consistency. Do you vary the development time with temperature?
For normal RA-4, I always develop for about 2:15. My temperature doesn't drift so much. I have just missed printing in hot summer days. If I did it at, say, 30 deg C (there is no decent air conditioning in the darkroom I use), maybe I would shorten the time to, say, 1:30 to 1:45 or something like that. But, I haven't seen ANY difference in my range of 21...26 deg C with constant development time.
I have tried varying development time between 2:00 and 3:00; the difference is only in contrast and density, not color balance, and is VERY MINOR.
I cannot see any difference in how Supra Endura and Crystal Archive behave in normal RA-4 process. They produce almost identical results at 22 deg C. Fuji CA is a very little bit more contrasty and has a little bit more saturated look, and filtration differs a few units from Kodak -- similar to how much there can be variation even between the batches of the very same paper! IIRC, there was just
one APUG user reporting difficulties with Fuji CA in room temperature; and this one experience gets quoted over and over again. Whatever the reason for the problems was, we need more data points.
Color development step in reversal RA-4 is practically similar to one in normal RA-4, so this information goes for both processes. I usually think about them as one process, with reversal version just having one extra step at the beginning!
However, the way the First Developer acts is more dependent on the paper; as I have stated before, Fuji CA needs and can tolerate higher levels of both thiosulphate and bromide in the First Developer.