I have one. I bought it a little over a month ago at the local TSC. This is my first ZTR. I mow about 1 1/2 acres, somewhat rough ground, and some slope in areas, ~15%.
My previous mower was a ~12 year old John Deere LX173. I owned it for 10 of those years, and it was a good mower. But it was getting tired, the tranny would occasionally skip, and it needed tires. Plus, it was under powered. I could not wait too long between mowings or it would bog down. Too much deck (48) for too little engine (15hp).
First, let me say that power and blade speed is NOT a problem with the BBMZ! It almost seems that if the blades were pitched the other way, it would lift off. I was that impressed when I tested it at TSC. At home, the power allows me to mow in less than ideal conditions, damp grass, etc. It covers ground quickly, as well.
I wish I could say the whole experience was as glowing as the power. Three of the four zerks that lube the deck lifting mechanism will not take grease. I do not know why yet. A week after I bought it, it was taking too much cranking to start. Found out the throttle cable clamp was loose, and the choke was not engaging. I had to remove the whole rear engine guard to fix it. There should be an extension on the engine oil drain. It is directly over the electric clutch for the blades. I had to make a custom funnel out of a plastic bottle to keep from soaking it. When you change the oil filter, you WILL get oil all over the rear deck of the mower.
As far as the cut... As I mentioned, my lawn (heh) is a little rough. Not terrible, but it's no fairway, for sure. The 48" deck hangs somewhat rigidly from the mower frame. If a drive wheel drops into a low spot, instant scalp. I'm mowing at 3 1/2". The anti-scalp wheels on the deck are too high, and are not adjustable. I wish they were.
I mentioned that parts of my yard are sloped 10 - 15%. If I mow cross-slope, there is a difference in cut height where the rows meet. The downhill side always cuts a little shorter that the uphill side. Not a lot, but it's noticeable.
Even with the excellent blade speed, the deck accumulates a lot of packed grass. If it's damp, probably a five gallon bucket's worth for every mowing. Again, due to the power the mower never bogs, but when the grass is too packed under the deck, it will "blow chunks". Scraping the crud out is no picnic. The deck is not "easy off" like the one on my old Deere. Maybe that's a characteristic of ZTRs, I do not know. Anyway, I have to put the front of the mower on blocks and scrape away with a 2" putty knife. It doesn't take too long, but it's not a pleasant job. There is no hose fitting through the deck. I do have a pressure washer, maybe I'll try that next time.
My last issue may not be directly related to the BBMZ, but could well be the fact that I'm using a ZTR on sloped ground. When going downhill, this mower is very hesitant to turn, especially if the grass is wet. I must be going very slow, and be very careful on the sticks to maintain control. What often happens is I will back off the stick on the side I want to turn towards, and the wheel will slow its rotation, as it should, but instead of the mower turning, it continues straight and the wheel simply starts skidding over the grass, frequently peeling away the grass as it slides. This is especially noticeable if I try and angle downhill. The mower wants to head straight downhill, and there's not much I can do to stop it.
I am adapting to these idiosyncrasies. I will replace the bad zerks, my custom funnel works OK for draining the oil, I will clean the rear motor deck after changing the filter, and put up with scraping the mower deck.
If my lawn was smooth and level, the cut issues would probably disappear. This thing would cut FAST on a flat smooth lawn. I am figuring out how to best cut the sloped areas. Even with having to be super careful on the slopes, I can still save about an hour (30%) over what it used to take with the Deere.
As I mentioned, this is my first ZTR. With the Deere LX173, I could relax, daydream, scratch my nose, etc, as I was mowing. Not so with this. It requires full attention (most of the time), and no nose-scratching or before you know it you'll have turned a 180. It's fun to drive.
I've been toying with the idea of putting chains on it, assuming there are no clearance issues... It may help with downhill control. Or it may insure than I'll make giant ruts every time I mow.
Anyway.... I needed a mower. I wanted to try a ZTR. I bought the BBMZ. It's powerful! It has some issues. It's true what they say, ZTRs don't do well on slopes (at least not this one). But I'm managing.
...hope this helps someone.