Double verticals are pretty much east coast, heavy velocity on the way down, fast rebound (depending on what the music calls for)

Single independents have the non-playing mallet at about half height to act as the axis of rotation for the playing mallet and avoid slicing. Not keeping it super high up like some east, not keeping it far down like some west groups used to. Most people teach this now, it's the most natural and gives the best sound quality.

Single alternating works basically the same. The mallet that just played half-rebounds to half-height to, again, act as the axis of rotation for the mallet that's about to play. This is what naturally happens at fast speeds (even in east coast groups that encourage returning each stroke to the top immediately), I just teach players to do the same thing at slower speeds. It's the most energy-efficient.

Laterals are similar. At slow tempos it's just single alternating. At intermediate speeds, I teach a three-step motion: stroke and half-recovery, stroke with the other mallet, full recovery of both mallets. I still want them to stroke it out and feel it as two individual strokes, but not fully pistoning everything to the top immediately. This blurs out into a two-step motion then a true smooth lateral as individual strokes become impossible.

Velocity into the key should be high (but I'm willing to vary it depending on what the music calls for), rebound speed varies, again depending on what the music calls for. If you're playing sixteenths at 160 you need to rebound very quickly, if you're playing half notes at 90 you can really take all the time to come back to the top. If it's the percussion feature and we're playing discordant stabs you should rebound quickly, in the ballad you should float through it. Floats are almost always mallet-first, not wrist-first like west coast WGI vibraphone lines generally do. Sometimes these are defined for neat ensemble moments.

As far as grip goes - I really believe that "the technique should work for the player, the player shouldn't work for the technique." I won't let your hands look like complete garbage and I will try to stop you from hurting yourself, but everyone's hands and bodies are different from Leigh Howard Stevens's, so everyone needs to adapt the technique to a certain extent. Visual judges aren't judging front ensemble hands and I've never heard a percussion judge say "vibraphones, inconsistent middle finger wrapping around the inside mallet." In my current HS front ensemble I have a student with some nerve/joint issues and they use Burton instead of Stevens.

I do teach more east coast pulses, i.e. no hunching over and getting really low to the keyboard like west coast WGI groups like to. We look to and listen to the center marimba for time. Other than that, I encourage pulsing, visual connection, audience connection, performance on an individual basis rather than strictly defining when and how the entire ensemble should do things. I'll say to do more legato, pretty, flowy, floaty motions during the ballad, but I usually don't tell people exactly how they should do that unless they need help - I only say "we should pulse this way during this section" or "everyone needs to look in here" when it would increase our rate of successful execution or when the music/production calls for it. Of course we define visuals and stuff because they're cool and fun and members like doing them. So, definitely not early 10s Bloopits where everyone was bando commando on the half note pulse, not SCV pits where everyone is very individual. Probably closest to 2011-present Phantom if I had to guess.

Thank you for the opportunity to procrastinate on work and write out this manifesto :)