I commute to work and ride all year in detroit. I see a lot of glass on the road and try to avoid it. My worst year was 7 flats. So far with about 3000 miles ridden this year I have gotten 5 flats, despite trying kevlar hard case tires. In past years I have tried the plastic liners. I still got flats with them.
I am now considering getting airless tires for both of my bikes.
I saw 4 web sites:
www.airfreetires.com
www.amerityre.com
www.greentyre.co.uk
www.nu-teck.com
If you buy them let me know how the install and ride are.