Go for the Echo SL
Super reliable freewheels with more than enough engagements.
However, go for the Echo TR rear hub as against the Trialtech. Heard of a few people stripping the threads on the Trialtech Hub.
Tartybikes also offer the option of Custom Hub Modification, in which they will shorten the hubs axle spacers if your looking to run snail cams in a horizontal 135mm spaced frame