I run an eno, on 170mm tensiles. Would like them a bit shorter cranks as i like pedal gaps, but they are good for gaps and such.
An Eno is better than an ACS. Thats a fact. But they cost alot more, some people think they cost too much, they're probably right. An eno is 8 times as much, but they arnt 8 times better. i would say 3 times as good. :P
They do tend to slip more than i thought they would, but mine is getting better. I think they like to get worn in, like a disk brakes. But they only slip when your are riding about, and not trialsing.
I also noticed that they tend to be quite restrictive, normaly you can hold a freewheel in you hand, and you can spin it with your finger. With my eno you coudnt, but it still turned of course. not that it realy matters, as you don't realy need it to be 'free' on trials. but still, i dont know if that was just mine....
Eno also feel MUCH stronger, it feels like you have the freewhel on the back. its feels like it can take the torque.
I would definatly get and eno if you have the money, but acs's do the job fine.
i can't belive you are running a dicta :S they normaly dont last 3 days.
:P