I bought a 1523 this spring. It's more equivalent to the Kubota 7610/2410(68.5 cu.in.)than the 7510(61 cu.in.). I love mine so far. I've never been short on power with anything as of yet. I have used a 60"RFM, 49" medium duty Tiller, and 30" dirt scoop with plenty of power to spare. I like the slightly higher ground clearance over the GC2300 subCUT. I didn't really want anything bigger than the 1523 for my uses. The 1528/31 have a longer nose(overall lenght is 10" longer) and have wider axles. Just for me personally, I liked the overall "look" of the 1523 better.
When comparing other brands(JD,NH,CI etc.) of the same size model(small-frame CUT), for me personally I liked these things:
....shortest lenght to fit in my garage - 102" (others =106,108,109")
....HP rated at lower rpms - 2600 (others = 2850, 3000)
....metal hoods, fenders,etc. vs. plastic (I know some like plastic better)
....higher ground speeds 12 1/2 gear, 13 1/2 hydro (others = 10.5, 11)..Okay, so this is not really anything worth mentioning....
....Lower overall height - 77" (others = 81, 89")
....and Price - $9,600.00 (others = 12,500, 13,000)
These are all little things, and I would love to own any of the other name brands. I feel there's close to equal quality with all of them. What it really comes down to is which tractor you'd really like to own the most. When I do my soul-searching, what probably influenced me as much as anything(sad to say) was that I liked the Massey I grew up with more than the other tractors we owned.
.....Back to the subject of my review, so far I have have no trouble with my 1523. All bolts, parts, etc. have been put together for a nice fit and finish(no rattles or quirks).