Well, if you're going to look at the Kubota B series you might as well start at the top

The B3030 is the top of the line B series. Along w/the B2630 they are considered the premium B series. The main diff between the 2 is the B3030 has a 30hp 4 cyl diesel and the B2630 has a 26hp 3 cyl diesel. Oher than that they are virtually identical.
Some of the features that set them apart from the std B's (B2320,B2620,B2920, B3200, B3300 & B7800) are:
1) position control 3ph. the std's have the 1/4" valve.
2) slide & pin 3ph arms. the std's have turnbuckles
3) tilt steering wheel, n/a on the std's.
4) better cruise control
5) higher hydraulic output
6) bigger frames & wheels
7) hydrostatic steering, the std's have power steering
The B3030/2630 use ground contact MMM's (similar to your Simplicity but no long rear roller) and the new std's (except for the B7800) now use suspended "BX style" MMM's. As you probably know, theres +/- for either and the debates have never been settled on which MMM produces the best cut
The B3030 & B2630 models have been around since approx 2006 and are due an upgrade as Kubota seems to redo the models every 4 - 5 yrs. The stds were just upgraded last yr.
The 2 main upgrades the std's got were:
1) all models now have 3 range HST's (previous models B7510/B7610 were 2 speed)
2) The B2320, B2620, B2920 went to suspended MMM's but the B7800, B3200 & B3300 retained the ground contact MMM's.
The B3030/2630 have 3 speed HST's.
When the B3030 1st came out there was "some" complaints about excessive vibrations in the steering wheel and HST pedal when operated at pto rpm. The majority of posters said it wasn't a problem for them but Kubota did come out with some rubber isolation on the steering assembly and I believe on the floor pan. I have personally operated a B3030 and never noticed any vibration but if you do a search on it you should get some hits.
The B2630's 3 cylinder has never been reported to have this vibration (as far as I know).
Some folks will recommend the B2630 over the B3030 as it costs less and has nearly the same capacities (3ph & FEL) and the same frame and wheels.
The main advantage the B3030 has over the B2630 is that it can be ordered w/a factory air conditioned/heated cab. It's the smallest tractor of any manufacturer that offers an OEM air conditioned cab. The OEM cab cannot be added after the fact, it has to come from the factory preconfigured. Search you-tube for B3030 snow blower and you'll see some mighty content folks listening to tunes whilst they clear the snow
When I grow up I've decided that I will be getting the B3030HSDC and mow my lawn in air conditioned pleasure
That B3030 you've posted is barely broke in. It should have already had it's 300 hr service done too.
I don't have the spec's but the digging capability of that BH is pretty impressive.
I see it doesn't have a MMM. That can be an $1800 to $2800 addon depending on whether you can find a good used one or have to order a new one. An RFM is an option that'll be less expensive if you do want to mow w/it.
Brand new a pkg like that "may" have run around $24K- 26K). Thats a nice pkg
Good luck SJ, let us know how it goes.
Dave