I've had very strong feelings on this subject for a long time. In every single aspect, a forestry style bucket/dump is a compromise. You compromise boom reach because the boom is mounted in the middle of the truck. you compromise chipping ability because the chipper is always on the opposite end of the truck from the work area, and facing the wrong way. You compromise on time because you need to send the bucket off to the dump when the chip box gets full. and then you compromise on where you can dump because you need to stop and lift the boom out of the way before you can dump the truck.
Most tree companies with forestry bucket trucks end up not using the chip box because it's a pain in the ass. So they end up hauling around a huge machine which only gets used to half it's potential and a boom which is compromised because it's mounted in the middle of the truck and you have to work over the cab of the truck, so you lose 12' of side reach. A dedicated rear mount bucket truck is so much more useful there is no comparison. My truck has 49' side reach, enough to where I can back up to a small house and remove a tree on the opposite side of the house. If you need to use the bucket truck for extra hauling capacity then buy a big dump trailer. You can unhook it and leave it out of the way when working.
If you need a chip truck then get a chip truck, not a forestry bucket. You may try to excuse it by saying you can only afford one truck, but buying a forestry bucket means you will end up buying 3 trucks. You will end up buying another chip truck and another bucket truck to replace the forestry bucket.
I had a couple different forestry buckets and I'd have to agree with Brian. Many times trees were climbed vs using the bucket just to be able to back the chipper up. And then well, you still have that shitty chip capacity for the size of truck. That said it's just how it was in my market and still is. Not a single rear mount bucket did any of my competitors or I ever have. I overcame some of the shortcomings like the long drag if you're using the lift with a mini skid so it worked out decent for me where it could be used. But then that entailed another truck/trailer on site so I ended up with a separate chip truck that hauled a dump trailer which worked out ok too. It would get loaded with the brunt of things and hopefully by then the boom work was done and the rest of the chippings could then go in the forestry unit after moving it into the proper position.