I got the SS bucket, and have regretted the choice. Mostly because it seems to put the bucket WAY out in front of you. Having the bucket back another 6-8" would help with all capacities.
Having said that, I cannot begin to complain about the capability. I wouldn't want a narrower bucket. My rear tires are spaced out to 66", both for hillside stability and winter chains, so 66" is a good bucket width. I have handled 1200+ lbs of concrete blocks, no problem. I've dug out rocks too big to pick up, but could push them around OK. Digging into a hillside, I can always to get a heaping bucketful of dirt/sod. With R4s, I lose traction long before I loose bucket capacity.
If you are having lift problems, check the hydraulic pressure. I'd have the dealer adjust it, or at least call him and tell him what you are about to do, and the pressure you are adjusting to. The manual on the loader says 2347 max psi.