I went with a Salsco 627XT 6" hydraulic feed. They are manufactured in Connecticut and are very well built. It has dealt with everything I've thrown in it and sounds like it could meet your needs. Even though it's labeled a 6" chipper, the opening is 6 x 12". I've chipped 10" pine & fir trees by ripping the trunks in half with the chainsaw first and then feeding them in. It only slightly slows the tractor.
I like the hydraulic feed because it allows you to set the feed rate you're comfortable with. You can also reverse the piece you are chipping if it isn't going in right or if, as others have said, you start to get too much leafy stuff clogging it up. The manual feed chippers work well also and I wouldn't rule them out. They are significantly cheaper and less complicated. The Salsco 627 is the manual feed 6", similar to the Wallenstein BX62. Both are good chippers. I watched a few videos of the chippers I was interested in on youtube before deciding.
I like the hydraulic feed because it allows you to set the feed rate you're comfortable with. You can also reverse the piece you are chipping if it isn't going in right or if, as others have said, you start to get too much leafy stuff clogging it up. The manual feed chippers work well also and I wouldn't rule them out. They are significantly cheaper and less complicated. The Salsco 627 is the manual feed 6", similar to the Wallenstein BX62. Both are good chippers. I watched a few videos of the chippers I was interested in on youtube before deciding.