Between me and my dad we've done hundreds of thousands of square bales using just an H and an M so I'd suggest small squares as well, unless you find a good deal on that 1734 baler. I echo what Edd in Ky said, especially as you don't want any waste with only ten acres of hay and trying to minimize grain use. Also with your small tractor trying to haul even small round bales out in deep snow will be tough work. I only feed squares to my own stock and when you are dealing with muddy hillsides or heavy snow and a small herd of cattle, it's a lot less aggravation to just walk out to the barn or take a truckload along the road and put out square bales in the field by hand. It snowed ten inches here yesterday and I just got back in from doing that rather than messing with a tractor and wagon. Two years ago when it rained nonstop for months and the ground was so saturated that even hillsides were laying water lots of people were sliding down hills on their tractors while trying to feed out rounds.
The few times I fed out rounds I ended up spending an hour with a pitchfork in 10 degree weather breaking it apart and putting it all into little piles several feet apart, the same way I put out squares by kicking the sections several feet apart. There's zero waste that way as they don't lay on it or step on any of it, and minimal damage to the field from the animals standing in one place eating. But it's a lot easier to kick apart squares than rounds
As far as grass fed cattle go, I run mostly black angus like everyone else around here but this year for my eight breeding cows I borrowed a Red Devon (aka north devon) bull from a guy five miles down the road who runs a larger grass-fed beef operation. That breed marbles a lot better on grass only than most beef cattle and also do well on marginal pasture. They aren't popular as a feedlot breed because they do better on grass than grain. He's switched to them several years ago and loves them because they make nice grass fed beef and are extremely docile for beef cattle. They are a tiny bit smaller than black angus (he's a shade larger than my cows and definitely smaller than an angus bull and CALM). I think I'm going to buy some females off of him next year myself and phase out the angus. Note that they aren't the same as the south devon or the american milking devon. They look like a slightly smaller red angus, with some noticeably different features that means you can tell it's not an angus when you look closely.