I just did a quick search and I couldn't find where anyone has review the AMK Thermo-lite bivy. Does anyone have experience with this bag or the heetsheet blanket? Thanks.

The regular heat sheet style or the 2.0 style?

The Heatsheets Bivy is not made of Thermolite.
The Tlite is a heavier and feels more like a fabric. The bivy takes up about the size of 3 or 4 HS bivies. The Tlite has a general "sleeping bag" rating of 50F which means it will keep you comfortable above 50F but it will HELP keep you alive WAY below that. Think; Heatsheets-summer, temperate weather, "just in case".
The Tlite is more-colder weather, very possibly overnight, UL-sleeping bag.
Bill

I have a AMK Thermolite II bivvy in my BOB for emergency shelter. I like it.

Thanks for the input. I'm thinking about adding them to a kit on my atv.

I have the Thermolite II as well. It is much smaller when packed than any normal sleeping bag, and you really can easily roll it back up and get it back in the sack. I got it for emergency use, but tested it out a few times. I don't know how many times you could use it, but it isn't really flimsy at least. It was about 60°F when I used it and I was warm, but then I don't like being hot anyway. Yes, you could call this model an ultralight sleeping bag. Seems worth the money. The Heatsheets bivvy is more disposable, but looks like it should last more than one use. I have not slept in it yet.

I've used the Thermolite as a lightweight sleeping bag for backpacking in July. I brought along a fleece sleeping bag liner which is light and comfortable that I put into the Thermolite. I slept great. The Thermolite is reusable, and it doesn't crackle and rustle all night like a space blanket. I don't know that it's as strong as a regular sleeping bag, but I haven't had any problems with splitting, cracking, tearing, etc. I generally carry the Thermolite on colder weather day hikes and a simple space blanket bivvy on warmer weather day hikes.

Here is an old review of Thermo lite