"One of the caveats when using v/s in the 75/76 is that you lose 'alpha protection'"
In VNAV and FLCH, the autopilot and autothrottle won't let the speed get too low or too high for the current aircraft configuration. The aircraft pitch and thrust will change to prevent this. With V/S, however, there is no speed protection at the limits. E.g. If you dial in a 6000 feet a minute climb, it's not likely that a 75/76 will be able to maintain this climb rate for long periods (even at low weights and max thrust). However, the autopilot/autothrottle will keep aiming for that climb value... until the aircraft stalls. Similarly, if you dial in a large descent value, the aircraft will exceed airframe/gear/flap/mach limits.
Regards.
NSEU.