When we bought our machine it came with the avant grapple on it and didn't want to wait for a bmg to come in. We returned the grapple in a week for a bmg. It couldn't get around moderately sized brush piles, felt heavy on the machine and didn't have the grip for large logs.
A lot of it depends on how you work. For us doing a lot of work in back yards and rigging down long pieces to our avant being able to just run a long rig through the chipper is faster than cutting and stacking for the grapple truck.
We definitely have more capacity for brush with chipping over...
We started with a grapple truck as well and got going in april last year. Follow the manual and keep things greased and be prepared to have some big repair bills. We have $10k into work on the hydraulics already. We were also able to dump for free all last year.
The grapple truck first worked...
Storm work $23k tree, 42" white oak uprooted through a house. Standard tree work $13k for a 5' diameter 110' lightning struck cottonwood with a 90t crane from the drive way and a 40t kboom for a tie in
Built my terminal rigging point over the sidewalk and ran the main rigging line through the ring on ~80' of three strand.
This allowed the grcs to lift to a closer point over the garage then lowering the 3 strand with the portawrap allows a controlled drift out to the terminal rigging point.