the only benefit to a blend is that things start up a bit quicker because of the fast acting ester, as opposed to just test cyp which takes a good 4 weeks. I prefer to do things myself though and specify exact dosages (hard to do with a blend), so if I want things to get going quicker, I will simply front load my long ester test c with test propionate for the first few weeks of the cycle.
eg.
test prop - 150mg eod weeks 1-4
test c - 500 mg a week weeks 1-end
a blend that contains test prop is best to pin EOD for more consistent test levels .. however a long ester test like test c can be injected only twice a week and blood levels will be very stable.