"Time to get to low tow"?!?!
You're doing it wrong.

Towplane and glider start rolling, glider lifts off and stays a few feet off the ground in ground effect, towplane lifts off and climbs out, when sight picture looks correct, glider starts climbing.
The propwash is not really a factor since it has not quite come together yet with normal ropes, maybe felt a bit on rather short ropes. By the time the turbulence has come together, it's over the glider.

BTW, I am not an AandP or IA, just an ex CFIG, long time glider pilot with some power time.

As to a release with a roller, any roller is better than a sliding surface, although keeping it rolling while operating on grass or dirt may be an issue.
On a sliding type release, at least make sure the edges of the hook where it goes into the release are smooth, not mushroomed out. A flat file now and then to smooth it out helps this.
Also some lube on release cable guide rollers, inside guide tubes and release pivots helps out a bit.