I have a 50" LandPride tiller with Side-Shift capabilities, it is 2 years old, and I think it only cost me about $1100 when I bought it. I'd be surprised if $3500 is a competitive price for a tiller that is only 20" wider and does not have the Side-Shift feature.
As to quality, LandPride is generally considered one of the better brands, but maybe not the highest tier brands. Howse, as KiotiJohn said, is generally built tough but considered a value brand. My friend sells Howse equipment, I've borrowed many of his "demo" pieces and generally don't like the paint quality and weld quality, but the stuff seems to hold up. I think it is a decent value, but not what I would choose to buy as it often lacks little design features I've come to appreciate. That said, I've never tried a Howse tiller, there are many TBN members who have gotten years of service from their Howse tillers and think they are good.
As for REVERSE rotation, realize it takes more horsepower to run a reverse rotation tiller than a forward rotation tiller.
As to size, I can only relay my experience. I use 24 and 30 horsepower tractors. At my home I have black sticky clay and can easily bog down the 30 hp tractor while running the tiller, at my other property I have loam with sand and the 24hp tractor EASILY will tear right through established sod with the tiller. So please consider your soil conditions!!! With light soil you can easily use larger implements than you can with heavy soil. I've had similar experiences with box blades. At home I can stop my 24hp with a 48" box blade, but at my other property, the same tractor can handle a 60" box blade. At my home, the 30hp tractor just manages the 60" box blade.
