yeah but the issue is on flats on your balls can be really hard to stay on the pedals especailly with out nice spikey flat pedals, and grippy flat riding shoe with 510s
If you or anyone insist on riding XC rides on flats I highly suggest getting nice flat pedals(which are ironicaly more costly than basic clipless pedal ) and shoes like the 5'10s with their grippy out soles and stiff bottoms. Trying to ride crap flats with normal shoes is basically a disastrous.
with that said for the most secure pedals to shoe combo nothing beats clipless which are called clipless because unlike the old bear cages you shoes are not strapped in but can actually release.
There is no disadvantage to clipless to vast majority of riders MTBing. If you are doing gnarly jumps/skinnies than yeah maybe flats are better but the vast majority of people spend more time pedaling or on sections of trails where clips are beneficial.
I started Diane on clipless after only a couple trail rides it is basically impossible to even ride easier trails around here on flats with out Ninja like skills. but this is what I did to eliminate "clipfalls"
First get SPD from shimano and set the tension really loose. Time's are ok and CRANK BROTHER suck for everyone but especially for beginners as the pedal have very inconsistent release they suck for everyone because they break. I personally have used the cheapest Shimanos for year with out any problems. I have never broken a single pair!
less than 25 bucks
Second - get shoes that fit your feet with a stiff enough bottom and grippy out soles. The last one pretty much eliminates all manufacturera beside Shimano AM shoe, 5'10 and Teva clip in shoes , and the entire Mavic line. Something like Sidi or Northwave have ball bearing for soles. My mavics have vibrim for an outsoles.
http://www.pricepoint.com/Brand/Mavic/Mavic-Alpine-Mountain-Bike-Shoe-2013.axd?gclid=CMWsiI6P6r4CFQGPOgodZ1kAwA these are so much better than cheaper shoes its Sin that the other manufactors still try.
I personally use their WC race shoe the Fury and its on the few thing I own biking wise that is literally top of the line. My legs are simply put way to strong for my feet and with Carbon especially on my single speed my feet fatigue really fast.
now that you have you clipless shoes and pedals and cleats were installs by someone who knew what they were doing your next step is this.
DO NOT GO MOUNTAIN BIKING
I know that sounds harsh but honestly go find an open grass field. and practice unclipping and clipping in until the only thing you will ever know how to do. This could take a couple hours. The majority of people who 'try" clipless strap on their shoes and head to their normal trails and then complain because they could not get out. Well no shit sherlock you have to practice moving your heel out to unclip. the real irony here is I can get feet to the ground quicker with clipless than with flats because of the way you move out.
After you have basically practice makes permanent your unclipping move in theory you should never have clip fall. This is exactly what I did for myself, and what I had Diane do. I have literally never had clip fall on SPDs...although i had about half dozen on Crank brothers and will never ride those pedals again......and Diane has had maybe 2 in her first almost year of mountain biking. If I had to guess Diane has taken less falls with clips than she would have with out clipless. I would also be extremely limited where we can go because trying to climb rooty and rocky steep uphill on flats is basically impossible.
to put it another way I am not good enough to ride flats on my local trails, in fact even if I was good enough I would certainly be slower, and I would certainly "dab" more.
tyler this is response partly to your PM.