IMO stay with the Ohlins in the rear. In fact, that's also what Hygear recommended when I asked them that very same question several years back. The reasons are: Ohlins shocks are known worldwide as one of the best shocks money can buy. They are a quality shock that are adjustable; (compression, rebound, sprimg preload) rebuildable, and revalveable. If you are happy with the shock action, there is no maintenance other than the occasional rebuild. If you would like a little more more firmness and ride quality you can go with one of Hygears twisted spring kits. I'm very happy with mine. The only downside to the Ohlins is the electronic solenoid wiring which has VERY questionable durability. The wires are very thin and break easily leaving the electronic adjustment useless. Replacement, while not overly expensive, is a PITA. The only solution to that is to shield the wiring harness and zip tie it very well. In fact I have a service bulletin that shows how to do it. Some see the added weight of the Ohlins compared to the MegaFloat as a downside also. However, the Ohlins will never go flat!
The MegaFloat also has a narrower range of operation. When setup for comfort, it hits hard on bigger bumps. And when set for bigger bumps is to firm (or harsh) for smoother trails. These are some of the reasons Yamaha moved away from that shock. The air adjustment is not very convenient on the trail either.
