Looking at the rig options guide on the website, the Javlin features the same 'folding tabs' as UPT has on their containers. I had that on a previous rig, and had it modified by a rigger to what's sometimes referd to as 'drop stitch' method. Essentially having the normal corners, but not sewn up fully, and instead opened up about 50% from whats standard. This is enough to allow the bag to leave fully straight/backwards, but enough 'corner' to make the rig pack nice.
The folding tabs and open corners for me created a but of a saggy shape when packed, and the rig (cosmetically) never looked as nice as I wanted to. How neat it looks with the folding tabs will mostly depend on the canopy sizing I guess.
I know UPT (on request) does offer the 'drop stitch' version of open corners, so perhaps worth asking Sunpath as well, should you prefer that over the folding tabs.