I purchased a Sospenders vest ~ 5 years ago and it had three negatives. The collar was uncomfortable around my neck, the cartridge was supposed to be replaced yearly and lastly I was concerned that it would inflate in the rain or when stored wet.
Since early this year I've worn a Mustang brand MD3181 inflatable vest. It is classified as a recreational inflatable Type II PFD. This vest while costing about twice of what my sospenders cost offers the advantage in that the collar area around the neck is soft, the cartridge does not need to be replaced for five years and inflation of the vest is caused by hydrostatic pressure. The bottom of the vest must be submerged four inches for the vest to inflate.
Whenever I fish alone (~30 times this year) I have worn this vest and find it very comfortable. I seldom wore my sospenders. A friend who purchased a sospenders had the same problem with the uncomfortable neck and purchased the Mustang MD 3181 and finds it comfortable.
Note: I don't have knowledge have what the newer Sospenders vests are like. Perhaps the negatives I found with my older vest has been solved.
No association with Mustang in any way.
The below informaton was copied from a web site selling this vest:
This PFD provides excellent safety, is designed for use in severe weather, and requires minimal maintenance. Used for over 10 years in Europe by Coast Guards and recreational boaters alike, the recently enhanced hydrostatic inflator developed by CM Hammar is exclusively available in North America from Mustang Survival. Hydrostatic pressure is applied to objects submerged in water. The hydrostatic inflator needs only to be submerged 4 inches (10 cm) for the hydrostatic pressure to open a pressure valve releasing a firing mechanism, automatically inflating the PFD. Low Maintenance - No inflator maintenance required for five years, unless fired. Reliable Inflation - Inflates under hydrostatic pressure, the PFD will not inflate prematurely due to rain, humidity or water contact (the PFD can be inflated manually by pulling the activation cord). Safety Inspection Window - Easily view the inflator replacement date and inflator status through the safety inspection window - green indicates ready for use. These inflators are maintenance-free for five years, lightweight, packable, comfortable and made of heavy-duty nylon.
Bob