My kid hits with an extreme semi western grip, where his knuckle is on #4 bevel but closer to the bottom bevel ( #5 bevel). He generates a ton of racket head speed and the balls still land a feet inside baseline. Some of the coaches he worked with tried to change the grip so the knuckle is closer middle bevel (#3) so he can drive the ball harder. Then there are these coaches who think his forehand grip is fine as he is able to blast his forehands with lot of speed and topspin. Should I work on changing his grip or leave it as it is? One of the coaches tried to change it but my kid absolutely hated it and had hard time keeping the ball in court and couldn't generate the same amount of power and spin. This coach insists on keep working on this grip before working on anything else like serve, backhands etc.
main thing i'd worry about is making sure the grip doesn't keep drifting too far west/hawaiian
are you tall? maybe that's why a coach is suggesting E (ala del potro), since being tall, your kid will have less issues with high balls.
also E can be a bit easier when taking the ball earlier, on the rise
personally i think SW is ideal, but i'm also a bit short 5'4"... and can use help with higher balls
but i also have made the transition from H to SW. H was developed as a kid because (a) my footwork sucked, and H a grip that was easier to handle high balls (b) because it let me access topspin more easily... but i made the switch to SW (closer to E then W) to be able to drive through the ball more easily
you might be able to compromise, keep SW (bevel #4), but only move it a tiny bit towards #3, but that can be tricky as the grip tends to drift back to where it was (unless you have some feedback mechanism to remind him). maybe the coach who wanted #3 was thinking he only wanted it a tiny bit closer to #3, but not fully on #3?