I have the same situation - 5 ac. and on the fence b/t a 2520 and 3320, (although the fence I think I should be on is b/t a 2320 and 3320.)
The question for me is whether I'd rather have the extra size and HP available at all times, or whether when a bigger job comes up than the 2X20 can handle I delight in running down the rental yard. I've read almost every 2520 thread and I'm pretty convinced that given enough time that tractor can do almost everything a 3320 can do with a few exceptions:
The fact is that the 2520 is lighter, less HP, less FEL capacity -- there will be stumps, roads & loads that the 3320 can do that the 2520 cannot. Sometimes a lighter machine can overcome that hurdle with time; sometimes not. I have time constraints, so spending three weekends on something the 3320 can do in one matters to me.
We had a Case 470 on lease when we started to build-out our raw land and it was great. At first. Once the big stuff was done, though, it was kind of a pain. Too big and bulky, way too much HP almost everything we did.
After the lease ran out I rented a Kubota (mid 20 HP as I recall) as needed and it was kind of a relief. More manoeverable, but there was clearly things it wouldn't do that that Case had sliced through, but no big deal. We used it for some light land clearing and landscaping and didn't try to do the things the loader/backhoe is designed for (digging really big holes).
Finally, I now rent a Deere 670 more often than I should and really really like it. There's not much the Kubota can do that the 670 can't given a little more time and forethought. For most maintenance type activities - gravel driveway maintenance, snow plowing, moving piles of material around, and light landforming it's just a terrific tractor. Easy to use, move and store. But the gear drive is a really back-breaker - no shuttle shift.
When I resolved to buy a new tractor I figured I just get 670-like 16-20 HP machine with HST and call it a day. I wandered b/t 2320 and 2520, avoiding Kubota b/c of the draft control and the comfort level.
BUT then ....
I started thinking. We're re-entering a build-out phase. We'll be cutting in new roads; taking down and moving timber; and doing some heavier landforming (cut & fill, grading, ponding). I was fooling around in the snow in the 670 and thinking about all that and realizing that it probably wouldn't be able to do much of that.
The 2520 is more tractor than the 670 to be sure, but as others have pointed out - how much more?
I went down to the dealer and looked at a 3320 and a 2520 side-by-side. Drove both. If all that I wanted to do was replace the 670 I rent, the 2X20 would win hands-down. But beyond that, the additional weight and FEL capacity of the 3320 really does make a difference. There's not much the 2520 can do that the 3320 can't, but the reverse is not true. The higher center of gravity & larger turning radius are definitely limiting, but for my intended uses it's probably not a good trade-off. The 3320 is bigger, but not that much bigger and in the long run it will do everything I can imagine wanting it do without having to contemplate runs to the rental yard for bigger machines. Note also that I do zero mowing -- I have a push mower for the tiny patch of grass we have. If I had to mow a lawn (not a field), I'd opt for the 2X20.
The last challenge is to get a decent price. I've been looking for a 12X12 3320 everybody has only hydro's; and the best discount I've gotten is 10% off MSRP. No too compelling.