I hesitate to try the stick-on little blind spot mirrors because of how hard they are to get off without damaging the OEM mirror. But as I get older its a bit harder to turn my head far enough to really look for a vehicle in my blind spots so maybe I need to at least give this a try.
You shouldn't worry about that; most of the time they'll come off without leaving
any mark at all, and the rest of the time what little mark they may leave is basically just a tiny bit of glue residue that's pretty easy to get off anyway! So I reckon you're stressing over something that's simply a non-event! :lecturef_smilie:
I've
NEVER had any difficulties removing them myself, & I've removed a fair few of them at the request of people who don't think they wanted them on their 'new to them' bike &/or car; usually only to replace them with
new blind spot mirrors just a short time later, when they've discovered thru their lack how useful they actually were!!
Most of these little mirrors are only held on by a small section of double-sided tape, and even the most 'stuck on' blind-spot mirror will generally come off with a little bit of help from
either heat or cold, maybe a sharp blade, and
juuust a little bit of effort; but seriously, once they go on & you work out how useful they are, you'll feel like you're driving with blinkers on if you ever drive without them again!
IF! 
So you really should stop sweating over the small stuff and do yourself a favour -
Fit the Damn Blind-Spot Mirrors!! 
hyea: After all, getting a little bit of sticky residue off your OEM Mirror at some future time is faaarr less of a worry than being hit by that turkey who blindsided you & totalled you'n your Spyder just cos you couldn't see them coming
in your blind spot until it was too late!! :yikes:
Personally, I prefer the round mirrors with a base that sticks to your OEM Mirror and a convex mirror mounted on a pivot an angle so that you can spin/swivel it around to change your view as necessary - most of the time mine are set to show me those 'blind spots' behind me that aren't readily covered by the OEM Mirrors no matter how carefully I adjust them; but then if necessary, I can dial them around to show me the ground immediately in front of/alongside my rear tire so I can carefully pick my way thru the sharp debris on the road; or spin them around so that I can keep an eye on that helicopter that's been sorta tracking me from up high & behind for a while

pps: Even though my blind-spot mirrors spend the bulk of their time covering my blind-spots, it's really '
extra handy' to be able to dial them around & adjust the wide-angle view as & when necessary &/or desired. :thumbup: