I've a Mono strap and a Comfort strap and find the Comfort one a little, well, more comfy. The weight displacement seems better.
In terms of standing. You'll find that you have a 'default' standing position when your play that you always revert too. It's just muscle memory. What ever this is, swop it over. So, if you stand with your left leg forward, try it with your right. The other thing is to turn your feet out wards slightly. It really feels strange to start with but it helped me a lot.
As a pro sax player and flautist, we were given lessons in the Alexander technique (posture etc) as the show I was working with we're sick of paying out for sickness!!! Again, it proved invaluable....