TSO'd Garmin WAAS navigators provide advisory vertical guidance on at least some approaches while non-WAAS boxes do not. It is kind of a cute trick but I tend to towards the dive and drive school of thought so for me they are mostly a reference to make sure I'm getting the dive right.
Remember, folks, that real ILSs do not all have the same approach angle. If I am reading the TERPS correctly (Ch. 2, Para. 244), angles can vary from 2.75 to 3.77 degrees on civilian approaches. If the approach calls for a high angle and the cockpit "situational awareness" box provides a TERPS "optimum" three degrees, things could get very exciting.
I think AdventurePilot' best course of action, paraphrasing Peter Lynch, is to "Go for a product that any idiot can run -- because sooner or later, any idiot probably is going to run it."
If we're voting, I vote no.