The 8H with the hydraulic feed might help when chipping larger stuff as you can slow the feed rate. So for a lower HP tractor it might be worth the extra $500.So do you feel like the 8H model is worth the extra $500? I can deal with $500 when I'm spending $2500 to start with. I can't deal with the wishing I'd already spent the $500 for a better machine.
I'm looking for flexibility (able to handle larger horsepower as a resale point, feed rate as a protection for my tractor, etc, etc.) and don't mind paying more for better usefulness and quality. I'm not unfamiliar with chippers. I've had a little mini-chipper (3" Murray) since 2005. I've run a LOT of brush through that little critter. And one of my specialties in my job has been industrial chippers (paper mills) up to 5000 HP. You ain't seen a chipper until you see a chipper that can make a 60 foot white oak tree disappear in 6 seconds. It leaves an impression.