I have purchased AwardGuard to protect my miles for about 6 years. I did so mainly because I had a lot of TWA miles and knew they were facing financial difficulties. Also I knew that the number of TWA miles protected by AwardGuard would be small, as compared to American, United, Delta, etc. and, therefore, AwardGuard may be able to protect these miles.
However, I was never real comfortable that AwardGuard had the financial resources to really protect my miles completely. I, also, was never able to find a financial accounting of the assets to back possible claims. (If a major Insurance company was backing the plan, I would have felt much better about it.)
When AA took over TWA, I decided to drop the coverage because: 1) AA (and other carriers I use often) are more stable than TWA was and 2) if one of the biggies defaults on its FF program, I do not see how AwardGuard would have the assets to make payouts. I imagine it would be a "rush" to cash in ASAP for all covered members and become a frenzy.
Perhaps others or Randy can provide more info on the "backing" of this program - but I have been unable to find it.