I have 4-5 IFR hoods/glasses but I found the "bestifrhood" to be the best. I just knocked out my IR last year and used it for all the training. It inexpensive and you should definitely give it a try.
The manual for the GPSS unit will have instructions for how to make it work properly. I was having trouble until I went through those instructions which tell you how to make the GPSS, AP and GPS all work together properly.