I've had absolutely no issue with the transmission in my LX. Perhaps in high range (which I rarely use) it's noticeably 'jerky', but if I'm trying to creep or make fine movements, I'm in Low range anyway. I use mid-range for pulling the trailer around in the yard, but most of the time, it's in low range for creeping. It is a heavy machine, and unless you've got a golf course for grass, it shouldn't be problem. I've got the SU model, which does not have the mid-PTO option. But it does have the [loaded] oversize tires, which is an additional 4 inches or so of ground clearance and nearly 1500 pounds of extra weight which is what I wanted for the possibility of putting a backhoe on it. If I were going to have a problem with jerking from the transmission, the larger diameter wheels/tires would aggravate it some, but perhaps the inertia of the loading in the tires smoots it out some. As for standing up to reverse, umm, that ain't gonna work. Move the treadle the tiniest bit with your butt anywhere but on the seat, you just shut your tractor off. I find mine to be very smooth. Very impressive machine. I'm not a real big guy (6'1", 180 lbs) and have small feet (Size 9) so I can get up and walk around on the operating platform of my LX. It's got a lotta room up there. The standard seat is pretty much the same as the Deluxe seat, except no arm rests. Very comfy. I can reach the toplink to adjust it if need be without getting off the tractor, too.
The only advice I have about the box blade is make sure it's wider than the back wheels/tires on whatever you get. The LX is going to require at least a 60 inch blade. If you're only going to be moving light materials with it, then the 60" bucket is a must for the extra volume. If you're going to be abusing the bucket some, then the 54" HD bucket might be the better selection. IIRC, the B uses the LA534 loader, and the LX uses the LA535. There's only 1 KG (2.2 lbs) of capacity difference. Negligible, I'd say. I THINK the LX has a slightly more capable 3-point lift. Are you getting anything really heavy? Doesn't seem so. That's a vote for the B. Unless you're a big guy, then that's a vote for the LX.
If all you have is .8 acre to cut, either an LX or B will be sorta like killing a housefly with a 20 lb sledgehammer. You may get the fly, but you're gonna make a mess doing it. The horsepower range is about right (19HP at the PTO), but there's way too much machine for the job. I think you're going to find a tractor that size too rough on grass, especially trying to make sharp turns, which is part of the procedures for efficient grass cutting. If you don't have any rough or muddy places, 4WD will be a waste of money because you don't need/want to use it if the tractor isn't burying itself or slipping and sliding. It will chew up the yard, even with turfies on it. To do the pushing/loading/blowing work, you're going to want some serious weight, and loading the tires will do a lot of that for you. I wouldn't advise the turf tires at all if you want to do loader work with it. If you have loaded tires, then you just added damage to your grass, especially if you need to turn sharply. Don't get me wrong, because I'm all about 20 lb sledgehammer fly swatting. I just don't like tearing up something that I've already had to do that to, i.e. the grass I've been trying to cultivate for 17 years. My yard ain't a golf course, I'm just trying to stop the erosion because the previous owners never picked up a leaf in the yard. To that end, I find a much lighter riding mower to be the better solution for the grass/leaf management. I got my LX for the digging and pushing strength in places where there isn't much grass and I'm trying to change that. I'm recovering nearly 3 acres that has been left feral for nearly 50 years. A riding mower for that is useless, and I'm getting too old to do everything the hard way. For that purpose I'm considering a 3-point flail mower that I can destroy stuff that would destroy my Husqvarna rider. I will eventually not need the LX, but on the other hand, I'm in no great big hurry to clear the lot. It's a hobby and the primary purpose is to make it less likely to find a rattlesnake waiting for me in one of the stump holes back there.
I don't want to talk you out of a tractor purchase, because having one has been sheer pleasure. They're great for heavy yard work, and you might even be able to pick up some paid work if you have the other attachments/implements and help pay for your investment. I'm just trying to give you some anecdotal information that is based on my experience with the LX2610SU, versus a riding mower for cutting grass. I already had the rider, and the LX purchase was for the parts of my yard where the rider is useless. I'm not trying to turn it into a golf course but I want to cover it with indigenous flowering bushes and things that will grow under the large trees and make it worth a lot more with some eye candy. What I do with the rider is the parts of the yard where the LX, while not useless, would be too much overkill. I like the smaller 46" deck on my rider because I don't have to worry about hanging it up on things and breaking it. I can scoot around stuff because the turning radius is VERY close to zero, and I also have a lot less clean-up work with the weed eater in the finished part of my yard. I'm cutting nearly 50% more grass than you, and I can do it in 2 hours with the bagger off, 4 with it on. A bagger for the rider is around $500. One for a MMM, about 6X that. I've toyed with finish mower ideas and asked some of the same questions you did. One thing I like about OTT, is if you want a candid opinion (as long as it isn't politics), you'll get a candid answer.
Just my $0.02 worth.