I do not have any experience with the Excell but the Buffalo has quickly become my go to bow for all occasions. I find myself stump shooting more than ever since the hunting season has come to a close. It's that enjoyable to shoot!
I picked up a 60"50# Buff a year ago and have since added a 45# and 55# Buffalo. As other members have pointed out, it's almost too easy to shoot. Very quick with great cast at longer distances, once tuned--silent. Each thread that starts about this bow, I have always chimed in because I cannot say enough positive things about it.
I have sold 2 of my Silvertips in the past 6 months do to the lack of time I have given them to shoot. Something I have never considered with all the bows I have owned before
If you are on the fence about trying one, you owe it to yourself to give it a shot, I think you will be pleasantly surprised.