Rating: 4 / 5
I pulled off the bite valve and it replaces fairly easily in order to convert it's use to a gravity filter. I made a gravity filter out of it once, connecting to the bite valve an old cut platypus hoser tube that still had the 28mm threaded cap fitting attached, so it could be attached to a second platypus. I would score it higher if I didn't have to 'rig' this system up. They could have easily included said items.
The 'dirty' water bladder gets strapped to the top of my MLD Starlite, and gravity filters into the 'clean' bladder located in the long, side mesh pocket. takes about 15-20 mins to gravity filter 2.0 liters. No burping is required since your're talking about bladders here, and not PET bottles.
When used as a straw, connected to an inverted platypus (again PET soda bottles create vacuums) it flows well enough to drink at a reasonable rate. I find that my cheeks don't hurt as they did sucking through the original Frontier filter straw. The main difference might just be gravity.
I've only filtered about 8 liters of clear creek water so far; I do worry about the longevity of the filter.