I have them. You don't? Go get one. Teles means SLR. You will ditch M2 and 90 in no time. Many professionals back then did. Nikon with tele, Leica with wide.
Again, it is nice to have small 90 Elmarit-M or Elmar 90 ltm. Just because
I have SLRs too - Hasselblads and a couple Nikons, but I've been using rangefinders for more than 50 years (certainly longer than those new-fangled SLR things ;-). Just works for me. I wasn't saying that rangefinders are appropriate for really long lenses, but a 90 on my M2 and 135 on my M3 work fine.