10-20 ton will get 99% of every thing done, bunch of people running the 7 ton electrics and doing ok. tonnage vs wedge shape, a big fat fast spreading wedge takes more brute force than a long thin wedge with a spreader behind it, and those fat wedges transmit a lot more force into the beam and foot plate assembly before stuff starts to split. Kinda like the difference of a 10# sledge vs a 10# splitting maul.