IFTA Crop Update12/02/22 (and Italy Study Tour and multi-leader apple mini-experiment) 

it takes the trees longer to fill the space. You're effectively making 1 tree take the place of 3-8 super spindle apples; so the early yields will be lower. Long-term, you're not going to see much of a difference year-to-year, once you get to full canopy fill. The trials in NZ are showing noteworthy gains in yields compared to TSA. The nice thing is that you can plant these 7'x7' on Geneva 890, M7, and Bud118 (if your soil is shallow and sandy like mine, otherwise might consider a Geneva 202 at that spacing (by way of reference, my TSA planting on B9 and M9 failed spectacularly, I ended up ridging soil above the graft to gain some vigor in the trees)) and keep your establishment costs lower due to a shorter trellis (my top wire is at 7', trees are topped at 8') and only having 890 trees/ac, versus 1200+ / ac for TSA and close to 2000+ /ac for SSA. The biggest thing for the espalier/cordon/hedged systems is that you are able to and have to move your rows closer together, this has the added benefit of making the orchard more pedestrian. Greater light interception per acre tends to increase yields, at the very least, I've noticed improved color and ripening consistency with the thinner canopy.

Yes, cordon, guyot, I had not made that connection. Wish I cold spend some time in grapes but apples keeps me busy enough!