Tele-Elmarit-M is an excellent choice
I think your dealer is trying to get you to buy something rather than giving you the objective response. I have it on the M9 and it performs very well and is plenty crisp. You can also get a nice one for $600 or so. At just over 200 grams, the Tele-Elmarit-M stands out as one of Leica's most clever designs and it tests very well - see Puts' lens tests for his take.
Another excellent choice is the Elmarit-M but that is quite a bit heavier.