Some info I've found looking for one myself, (and no you will NOT be able to use an 8' sweeper with a 25hp tractor
Using tractor hyd,
Simple easiest connections, can use it on loader or 3pt. Cheaper than self-contained.
Most 20-25hp cuts have too small hyd power. I believe they do make a 4' sweeper for the smaller ones? Can't swap tractor brands or share it with your brother or neighbors tractor unless they use the same tractor. Wholly dependent on tractor hyd capacity. Dependant on size of sweeper.
PTO driven, self contained hyd unit, pump mounts to PTO and hyd reservoir tank is on unit,
Any tractor can use it, no contamination between tractor brands or if you change tractor brands later. The pump just connects to the pto and the hoses go to the tank that is on the unit. (My 3pt back hoe is this way) Slightly more expensive. The pump may not work on a mid mount pto because of the pump size, around 8" wide. But there is a work around. Not as dependent on tractor hp. Not -as- dependent on size of sweeper.
PTO driven, gear drive,
Most smaller compacts can use it, less likely to stall than a hyd system of the same size. Cheaper than hyd systems. Any tractor can use it. Same hookups as a brush cutter. Not as dependent on tractor hp. Not as dependent on size of sweeper. Can work with a mid mount PTO?
For MY usage's I just need to move leaves, small branch's and the needles off a paved road. I have two other neighbors with 25hp ish tractors and two of us with 35ish hp tractors. I think the 6' would work "ok" with the 25hp tractors if needed as a backup. We probably have around a mile of paved shared road to keep clean so no huge amount of material movement.