Flat fix advantages: open valve cap, spray in, ride
Disadvantages: Tyre U/S
Puncture repair kit are a semi permanent (can be permanent) repair
Tyre can / may be fixable
3rd Option: the puncture GOO stuff the Army use in their vehicles: will seal a punture instantly, helps weight the tyre to the road (minimal)
I have used the Flat Tyre stuff... had a nail in a tyre, got me out of trouble as I was going to a meeting but the ****** cost of the new tyre hurts bad.
My Advice: DONT use the flat tyre stuff...