I've been very intrigued by the JAKL too. Would also want it in 300. Based on the forums, some seem to have them run reliably out of the box and others struggle to dial in the right setup. Think it gets more complicated when you add the can and run subs....or are trying to switch between types. I've been hoping that over time the prices come down a bit, but so far they haven't moved.
Lots to read here:
PSA JAKL Forum