I'm really enjoying having the M with me at all times and also wanted to find something to protect it a bit in transit....I had one of these( http://www.amazon.com/gp/product/B000F4U8VC/ref=oh_details_o07_s00_i01?ie=UTF8&psc=1
) leftover from my nifty fifty and it works great as just general protection to throw the thing in my work bag or in the console of my car. The fit is very good with the 20mm...just snug enough (I leave the strap hanging out).
While looking for something a bit more elegant I came across this and it is on the way (cheap enough to try):http://www.ebay.com/itm/170962069600?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
I'll try to report back....
I've also noticed the extra bump added by the cap which is exacerbated by the addition of a filter. In the interest of compactness I am beginning to lean toward deleting the cap and the strap if the "PU Leather" case works out (and definitely will not use the one that comes with it).
I have each of these around after adding a Cotton Carrier hand strap to each of my bodies and have yet to try them, but I can highly recommend the Canon camcorder strap for DSLR use if you are just looking for a bit of help in the event you lose grip. The neoprene OpTech should be plenty strong for the EOS M, however.http://www.amazon.com/gp/product/B00009V4G9/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1http://www.amazon.com/gp/product/B00137NMMW/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1
One last thing...the LowePro EX120 is just about a perfect fit for the M if you want to carry the two lenses, battery + charger, and a few filters/memory cards. The 90EX Flash MAY fit as well, but I don't have one to try it yet. http://www.amazon.com/Lowepro-EX120GRY-Camera-Bag/dp/B0001YM40E/ref=sr_1_2?s=electronics&ie=UTF8&qid=1374806949&sr=1-2&keywords=lowepro+EX+120
(I think I've contracted the same disease as Neuro given the bag/case collection I've built)