Apparently I'm not allowed to edit posts after five minutes, so here's the same post from above, but with some additional thoughts.
I've been carrying the new Spinal Tap for over a year now, and I've taken a good look at the new Grip bags in person. There are benefits to both bags, as well as a few drawbacks.
Voodoo ST Benefits:
Putter Pocket - Hands down the putter pocket on the ST is way better than the grip. There's no cinch mechanism to prop up a putter, but it holds more discs than the Grip. I currently have five discs in the putter pocket - three Judges, an Envy, and a Harp. It's a squeeze, but four putters fit comfortably. However, if you cram a bunch of stuff in the half moon zipper pocket on the front of the bag, then the putter pocket will not fit as many discs.
Better materials - The ST uses heavier duty fabric throughout the bag. This isn't to say that it's necessary, but the ST is built like a tank, and still looks new even after a year of play.
Bigger drink holders - The ST can carry a ton of liquid if you need it to. I've fit two 40oz hydroflasks in the side drink holders with ease. The two tiny outside pockets on the sides are also capable of carrying those green 32oz squeezable Gatorade bottles. You could theoretically carry 144oz of liquid without ever touching the inside storage compartments. I don't recommend carrying that much liquid on the course, but you can do it if you want to.
Larger Storage Pockets - The zippered side pockets on the ST are much more generous than the Grip bag. They're deep enough to carry multiple discs if you want to, and that's something you can't do with the Grip bags.
Exterior storage - The exterior storage on the ST is better than the Grip. It's much easier to attach a stool using the velcro loops on the ST, than the cinch loops on the Grip. The outside pockets on the ST are also easier to use, and are more functional.
Grip Bag Benefits:
Plastic runners/feet - The Grip bag has runners on the bottom of the bag to keep it from abrading, and to keep moisture from permeating the bag. Depending on where you play this can be an issue. This is one thing I really wish the ST had, and I've considered adding it myself.
Style/Color Options - There are way more color options for the Grip bags.
Warranty - It's a lifetime warranty for the Grip. Only five years for the ST.
Better pocket storage - While the ST wins out on storage volume. The Grip bags win out on storage organization. Their inner pockets and pouches are way more usable than the ST. The ST's pouches are too flat and restrictive to be useful. The only interior pocket that I routinely use on the ST is the pocket that's meant to store the rainfly.
Rainfly - The rainfly on the Grip bags seem to repel water easier than the rainfly that came with the ST. I prefer the location of the rainfly snaps better on the ST, but the Grip rainfly works better at actually keeping the bag dry.
In the end, the Grip is a more compact bag, that carries fewer discs, but makes more efficient use of its internal storage. The ST is a larger bag that is capable of carrying more discs. What it lacks in storage organization it makes up for in volume.