My main intended uses were hotels and car birdwatching trips, where a slight increase in bulk would not be an issue.
Pictures:
The main "cooking bag":

Instructions on back:

The measuring cup and mylar bag with all ten heating pads:

Inside the mylar pads bag:

A single pad beside the measuring cup (for scale):

A single pad beside the heating component of a FRH:

Cooking bag in use, wrapped in an authentic hotel towel:

Performance:
I've used it three times (so far), and all three times it was inferior heat-wise to an FRH.
On a positive note, it was considerably less "fussy" (no stuffing & no dexterity required) than an FRH, and it's better than nothing.
The smell is roughly equivalent to an FRH. The bag's instructions assume outdoor use, and provide no information about the fumes. I performed all testing (so far) indoors, so am somewhat concerned about this lack of info (I have not found a manufacturer's site, or any reliable info).
All three times, I just tossed the food (two Armour retort pouches, one Chef Boyardee can) in, just as the instructions say (placed with the longest dimension along the bottom, instead of "upright" as in the instructions' diagram). The third time, I was a lot more careful about placing the heating pad flat along the bottom.
The absolute worst warming occurred with the canned food, which was particularly disappointing given that this product is supposedly intended for cans. I used a regular 425g (15 oz) can (Chef Boyardee whole grain lasagna - nothing weird).
I suspect there are trick(s) that would improve performance, so please throw suggestions at me, and I'll try again.

If anyone's interested in trying this, Amazon has it for about $6.50 (it's been fluctuating wildly for months, but finally dived below $7 about two weeks ago) for the bag with 10 pads.
I'm in the midst of experimenting with several alternative heating devices, and would welcome reviews from anyone, particularly for things like car manifold cooking.

If anyone is interested, I can post up some experiences with Thermos Cooking, which is mostly Kate/Geek-proof, hence it must be MRE-Geeks-proof.

I've been meaning to post this for a while (wrote the first draft last Spring), but have been buried in Work. Gotta take some time off to play with fun mostly non-computer stuff.