I have a 3320 eHydro with 300cx loader, 448 BH, and grapple bucket, bought new last year and now have 127 hours on it. Loaded R4's, open station.
I wanted a gear drive but there wasn't one available within a workable time frame and the dealer gave me a PR price for a immediately available eHydro unit and I took the bait. Glad I did. I fully appreciate gears, but for my use the hydro has worked out fine and I now prefer it.
As for the rest of the machine, I chose the Deere because it seemed to be the best overall deal in the 30 HP class. I liked the ergonomics and construction quality and all other things being equal I wanted to go green just for old times sake.
I did not go for the 3520 because I had (and have) nothing going on that called for the addt'l HP, particularly at the PTO. If I needed to drive some big
chipper or something that the turbo might make a difference. Most of my work involves pushing, pulling or lifting and the 3520 wouldn't have made much difference to me. Not one minute has passed when I've since wished for something bigger. I use my 3320 for loader work, trenching, stump pulling, brush clearing, snow plowing, road maintenance and carrying hand tools. Occaionally, post holes, but not much PTO work at all and no mowing or disking. We have 5 wooded acres we're building out and I also like to help out neighbors with pools, plowing and trees.
Aside from power, the physical size has been perfect. Not too big, not to small. I've done some moderate land forming and clearing faster than a smaller tractor and slower than a bigger one, but haven't been turned back yet by either having something too big to get into a nook I want to get into or too small to get something finished within my time constraint. I've had a Deere 670, Kubota B- and L-series, a couple of skidsteers, and Case 470 and the 3320 has been the perfect fit for me among all those. I've had a few sphincter tightening experiences on hilly terrain so I bought the tilt meter and found that that data point helps my safety assessment. There's more than a few threads here on 3X20 tippiness.
Mechanically problem free except recently wore out a friction washer in the rock shaft control level mechanism - it's a 99 cent part and a several hour problem and hard to say whether it should have failed or not.
Design wise, this is the first tractor I've had that doesn't appear to have an outer time limit comfort-wise. I think the combination of the springy seat, tilt wheel, power steering, dual-pedal hydro, and loader control at my hip means I can run the machine for hours. One bummer about the hydro is that the constant fast idle can be nerve wracking, but I find that I'm usually over-throttling anyway and most of time can relax the throttle and noise-level and get the job done just fine.
The loader and backhoe spool valves are a little dissappointing from a mixing standpoint, but not a big deal. I can't combines motions as easily as I've been able to with other equipment, but my technique has been getting better. Also a few threads on the mixing issue here as well.
Finally, the support for someone like me - mechanically inept and really just a weekend warrior from tractoring standpoint - is super-excellent. This forum has been a constant lifeline and my local dealer is great. I chatted their mechanic up for a while about the rock shaft lever thing, it cost me nothing and he was glad to help. I think a lot of 3X20 owners are in my category - maybe not inept, but are landowners primarily using their machines for for their own account and not out for hire. There are very few questions that haven't been asked and answered in this forum.