Originally Posted by ragtoplvr
If you have less area below the piston, to do the same work, a higher pressure is needed. Higher pressures increase wear and need upgraded and more expensive materials. And the oil shears down quicker. Rebound damping is important.
So shaft diameter IS quite important and WAS chosen for many reasons. Or do not believe me and my years of hydraulic system design experience.
Ted Porter, of BeemerShop fame and Wilbers expert extraordinaire, told me pretty much the same thing when he was advising me on my shock purchase.
I went with Yacugar and the 16mm shaft, for the same reasons the OP should have...excessive weight. There's really no other reason to go bigger. The 14mm shaft suffers stress cracks only when loaded heavy. Otherwise, Ohlins and Wilbers are awesome!
Oh, and BTW; yes, you do have shorter service intervals with a bigger shaft and less oil.