Polyester thread in boat canvas is good for 5-7 years in the sun (here in the Northeast, where it's put away 6 month a year). If you want it to last as long as the fabric, have them use Tenara thread (it's made of Gore Tex PTFE fiber) which is impervious to UV.

When I bought my 9 year-old boat I took the nets and dodger to a canvas shop and had them back-stitch (over-stitch) the canvas and nets with Tenara. It's expensive but worth it.

(The aluminum channel has a 1" 3M Safety Walk tape strip applied. You can buy it in any hardware store. Without it the aluminum is very slippery and is a safety hazard. Fortunately the cure is very simple. The 3M tape holds up and adheres very well, even though it's out in the weather year-round.)