The Astral V-8 and the MTI Vibe are PFDs you’d use for similar things, and have similar attributes with only a few distinct yet significant differences. They are both class III vests with 15 pounds of buoyancy, both weigh about the same (20 oz for the V-8, 24 oz for the Vibe), and both cost about the same ($119 for the Astral, $95 for the MTI). Astral makes the V-8 in three sizes, while the Vibe is available in two. As shown, both are made in a nice hi-visibility orange, a good idea for swiftwater safety. Both fit closely, with plenty of adjustment for different body types and layers, as well as a few pockets. They are in short ideal PFDs for mild and moderate swiftwater packrafting.
The Astral is perhaps the most widely used such PFD, while the Vibe was introduced early this year.
The most obvious difference is the entry method and the type and distribution of foam. The MTI is a side entry, with right hand quick release buckles, while the V-8 is a front zipper and buckle. The buckle might seem redundant, but in addition to reinforcing the zipper during a rowdy swim the buckle allows the V-8 to vent when the zipper is undone. Venting is a major feature of the V-8, which is made from quite rigid foam with deep channel and holes cut into it, and a mesh liner. As can be seen from the photos, the majority of the foam on the front is low, and all of the rear foam is up high. The end result of this is that the V-8 wears quite differently from the Vibe, which has a tighter and more uniform distribution of much softer foam. The Vibe fits tighter with less strap pressure, but is warmer, while the V-8 venting is effective, but the design makes the PFD feel much bulkier.
Particular to packrafting, the thicker and stiffer foam of the V-8 make it substantially more difficult to carry securely in or on a backpack.
My preference between the two is the Vibe, though not without reservations. The better packability and fit are hard to overlook, but so too are the nice dual pockets on the V-8. Not only are they larger and easier to access while boating, they keep the pocket contents off to the side and thus keep them from interfering with re-entering your boat after a swim. The three sizes of the V-8 are also nice. With a 38″ chest I fit right at the bottom of the M/L size range, and right toward the top of the S/M size of the Vibe. In the M/L V-8 I have plenty of room for extra layers and a drysuit, while the S/M Vibe is under the same circumstances a tight fit.
M prefers the fit of the V-8, for the greater adaptability the segmented foam provides. She can drop the front section low and better cinch it around her waist, something the Vibe cannot do nearly as well. There doesn’t seem to be a way for a PFD to not be a boob-squisher, but the V-8 seems to have figured out a way to fit a variety of body types well.
Both are good options for packrafters, especially folks who run water where they want the security of a real PFD, but don’t need the complexity, weight, and cost of a rescue vest.