I had a Crary on a 320 A-C head on an l2, then I had an SCH on another 320 on an R-50. Between the two, I'll take the Crary hands down. It just did a better job and is a lot easier to change a single section on. On the 920 I have now, I run just the Crary hold downs, 'till I need the rest of the system. The hold downs work great, just eye ball everyday and if there's a bit too much gap, just crank it down a half turn or so. The plastic wear shims wear forever. The worst thing about the SCH is that if you run them tipped down at all, they tend to spear corn stalks in no-till beans, then start a pile dragging. Since they're reversible, there is no up-sweep to the guard point, either. That makes them more prone to digging in, too. If you tip the sickle up, to avoid it, you end up cutting higher than you want to. The Crary just does a better job, for me