When my apartment was burglarized in the spring of 2013, the thieves stole a Nikon D2Hs, D2x, a beat up 24mm f/2.8 Ai, Sigma 14mm f/3.5 with a chip in the front element and a 17-55mm f/2.8 AFS.
They took the bag that I took through several tropical storms (one was a typhoon in Guam) and then took through combat in Iraq. Also stolen was my roommate's Pentax K1000 with 50mm f/1.4 lens and some jewelery of hers. These things were easily identifiable as easily fenced and so had value to the burglars.
What was not stolen was a Leica M4 with 50mm DR Summicron, a Nikon SP with 3.5cm f/1.8, 5cm f/1.4 about $300 worth in reloadable Nikon cassettes and $800 worth in Eastman XX film right there in the cans. They actually opened my Domke bag to look at the Leica and Nikon SP with lenses but passed them by.
What they didn't know was that the Leica and the SP were each more valuable than the total haul of stolen gear (which I used for work.) The 3.5cm f/1.8 Nikkor was worth more than the two digitals as well.
My point is that thieves are idiots. If they weren't, they'd be doing some other line of work.
The worst thing that's going to happen to you by someone identifying your Leica is they will possibly interrupt a shot by saying something like "Oh, that's a nice Leica, what kind of film do you shoot?" Or something like that. Otherwise, you may get accosted by hipster girls and guys who shoot a Leica themselves or pontificate about digital, film or video capture.
As for the dot itself, you can paint over the red carefully and scrape the paint off the script quite easily. You could always do what I did with my M8 then my M9:
There is no sin in "defacing" the camera. It's a tool, not a monetary investment. Make it yours, get comfortable with it. Happy shooting.