a little lower rpm and most don't operate at rated from battery fade.
grab a fuel grinder and an 8 or 12 forge battery.... you'll change your mind.
batteries below 8.0 are for wood butchers, women and kids toys the way I use my stuff (okay drills and impacts etc too, but really almost all my small batts are for the wife's vacuums or the kids toys) its crazy to me they would sell a 5.0 with a grinder- its useless
all I do is metal work. I use either battery grinders or 15a 9" corded grinders. very rare to use anything else, a variable speed corded for fine work like stainless counters/ weld in sinks.
I mean if I have a production run and am going to grind all day at a bench, or on a big all day/week bucket job i'll grab a plug in, its not the everyday thing. the cost of the right batteries and grinders can be tough to buy in but once you do- worth it.
I typically have 4 battery grinders all fuel, and tend to need to replace one or two a year. I use the hell out of them. I've never worn out the gear heads like I do on the plug ins, or smoked one, but the inner bits seem to drag or make contact. so I toss them and get another. the newer they get the longer they seem to last, I can tell changes are being made.