Amir,
Thanks for your reply. Very helpful. I've ended up using the the SM7B instead of the RE20. At least for my voice I prefer the sound. But for interviews/conversations done at my office the RE20 is the "other" mic and does a great job! I can easily imagine how the RE20 would be a better fit for many voices.
I also have an old Sennheiser MD46. But I have to confess I don't really like the sound. Not bad at all, but a far cry (for me) from the SM7B and RE20.
What I wouldn't want to do is buy the M88 if it's not noticeably better than the MD46. I'm not expecting RE20 levels per se, but still something better than the MD46. I'd rather spend the extra money for the right "portable"mic. What's your take on the M88 compared to the MD46?