I've always stayed with the same ester throughout a cycle, except for switching to prop at the end. I've never switched to cyp, E sust, etc after running one of those for several wks. However, on the cycle I'm on now I'm fixing to switch from cyp to E because I got a really decent deal on some E...I'll let you know how that pans out...it should be fine though, they are basically the same thing.