Despite the fact that most dealerships still aren't going to use anything more than what is listed in their own workshop manuals as the minimum requirement there is almost no difference between C3 and C4 other than C4 must be low SAPS where as C3 can be medium or low SAPS.
Penrite make a C3 oil that is medium SAPS, Nulon make a C3 that is low SAPS, neither can be listed as C4 because of their SAPS level, however the Nulon SAPS level should be lower than the Penrite and closer to the C4 sequence.
The Renault spec doesn't even come into the equation as to which is more suitable, Renault built upon the C4 sequence for their own benefit, their test of course suggests they improved upon things but they didn't change the C4 sequence world wide because of it. The C4 sequence is a standard and that is almost identical to C3 it's main difference is the SAPS level.