With only 168 hours on your B2320 of course you need to find a way to keep it ! I'd never let that go even if I had to go buy something totally different to mow with. Do you have a loader out of curiosity?
To answer your questions:
My BX2200 is my "urban area lawn mower" on waterfront property where I mow an acre or so, use the bagger A BUNCH for leaves every fall, and use the little front end loader for both snow removal (now rare), mulch moving and chasing debris. So handy it is hard to exaggerate. I have a larger non-Kubota bucket modified to fit the BX2200 (LA211) loader just for snow removal or for larger loads of light material. We have had no snow this season but in some seasons over the past 2 decades we have had several inches at times. We've had the BX for 21 years now and got it with only 225 hrs on it. I've had to replace a few hydraulic hoses but no major problems of any kind in around 900 hours so far. Use it with a tiller and a blade here and there too. I had a receiver hitch mount made to bolt to the front of the frame and it makes the perfect "trailer mover" for moving my 14ft trailer in and out of a very tight storage location and around the property.
You also asked: how useful is your BX2200 compared to B2150? The BX2200 is as described above terrifically useful but that is probably because I live 75 feet from it. I live 330 miles from one B2150 and 265 miles from the other 2 B2150s. I do go to those locations once a month year round. I use one B2150 for cutting a lot around an old farmhouse with the belly mower and light 5ft bush hog work and moving trailers around, etc. I use wheel spacers on it so I can handle steeper ground & had to have the frame of the RC-60-21B deck on it modified to clear the rear wheels having 6" spacers. The other 2 B2150's are used in a mountain area for: One for snow blowing and FEL snow removal in winter and a 5ft bush hog in the summer for clearing higher grass and light brush on some lots. Also for spraying using a 12v tank sprayer loaded in the FEL bucket , moving gravel around, moving firewood, etc. The other one I use with a RC-60-21B belly mower for the close-in lawn mowing up there. The B2150s are 4 cyl and only rated a couple of HP more than the BX2200 but drastically more capacity overall.