I have heelclickers and I had a chance to ride
the same sled with Thundershift arms - a kit
from Cudney's.
In my opinion, the sleds acted about the same
in terms of backshift. We never had a chance
to run the two kits against each other, but I
was impressed with the response and feel of the
T-arms.
I love the heelclickers. I don't think you could
go wrong with either setup though. Much better
feel than stock.