Hey Simon and JSU,
It's a good question, and to be honest, I thought something similiar when I bought the m2 to compliment my m6ttl.....but in actuality, I only use/work with one camera at a time....
I bought that m6ttl about 9 or 10 years ago and used it everyday and took it everywhere. I bought that m2 along with an m3 about a year and a half ago from a member here as "back-up" cameras. I am not comfortable walking around with more than one camera swinging from my body...
I know some people use more than one camera when they are out shooting, but it doesn't feel right to me...so, I guess to answer your question, "no" it is not an issue for me because of how I shoot, but I can understand how it would be to someone who shoots 2 bodies simultaneously.
cheers, michael