Someone said they don’t need or want your equipment suffix, and that’s probably true, but only because they just assume these days that every aircraft is equipped with GPS. If yours isn’t – like if you’re flying a plane that’s /U – you might want to add the suffix, just so they know your plane's capabilities or lack thereof.
Back in the 90s and even 2000s, lots of planes didn’t have GPS and it was a lot more important to specify your suffix because GPS-equipped planes weren’t ubiquitous yet.
But these days, I don’t use the suffix unless I’m flying something which lacks an appropriate GPS navigator for the flight (if you’re IFR, obviously you need a certified GPS to be /G… if you’re VFR that’s also technically true but I used to report /G with a solid portable GPS because from the controller's standpoint it didn’t matter, and I had the capability to navigate to any GPS point VFR, which is what they wanted to know.)