Yeah I think Mulch will also still be an option so squeezing apples indeed might be doable. Keep in mind though only 40% of the apples are going to give you Mulch and I don't know how abundant Apples are from a regular farm, but I can totally imagine that they're not enough to keep up with the Sapling flow.
Walnuts, Chestnuts and Cherries only have a 5% chance to produce Mulch, so I dunno if they're efficient enough. How abundant are those compared to apples from a tree? I assume a lot more, otherwise it isn't really worth it I think.
Personally I like the MFR farm stuff, they don't use power when they're not doing anything (even the check to see if there is anything to harvest doesn't cost power). The Harvester does harvest all the leaves before going to the logs though and I think most other harvesters (Steve's carts, Forestry, CC) purely harvest logs and just pick up and saplings that drop. So all in all it's probably less efficient because harvesting all those leaves takes quite a bit of power, but for me it's still efficient enough to produce way more power than the farming costs (and I don't have to bother with Apatite, Humus or any of that stuff so it's still simpler than a Forestry farm
).
You get 250 work cycles out of one mulch, so i think one Steve's Cart farm is pretty much all you need for your mulch necessities. Normal fertilizer gives you 200 Work cycles, in comparison, and Manure gives the same as Mulch, but it's much more resource intensive. I don't even know what you get out of squeezing Cherries, though... I simply have no idea.
Chestnuts/Walnuts are produced in rather large quantities. DW20 had 3 in a Manual Farm, and it was like, a Stack every two or three minutes. It's pretty awesome. But, they are definitely NOT a primary source of mulch, apples are. You get between 0 and 3 apples per oak, although it seems that 2 or 3 is way more common, and you get 1 to 5 saplings from a tree. 1 apple gives you 0,2 mB apple juice, so it's 10 apples per 1mB, which is needed to ferment 1 sapling... So it's 10 apples per sapling.
The problem is the Apple Juice, not the Mulch, unfortunately. I'd think you'd need a dedicated Orchard with Apple Oaks on all 4 sides to be able to produce enough Apple Juice to be able to feed more than 1 fermenter producing Biomass.
What i've seen people doing, however, is using gates to make the Fermenter alternate between Water/Apple Juice. Basically, Two Pipes and some redstone logic. I can't remember exactly how it was set up, but it was very smart. I THINK it was If Tank = Full OR Liquid < 25% Don't Emit Redstone signal. The redstone signal was inverted with a torch, so if the redstone pulse was on in the fermenter valve, it shut off the water valve, so it wasn't pumped anymore, and the fermenter used up all it's water, and then the Apple Juice, until it reached below 25%, in which case the redstone signal was shut off, and water allowed to flow.
Pretty spiffy, you'll still get more than if using just plain water, but not as much as using exclusively apple juice. =)
