I was using a 2 inch grinder for weld prep on 3/4 inch plate for years. A new guy on the site in Buffalo just asked why I didn't use a 4 inch. | Boilermakers - Hub Chatter
Ever try to get into a tight corner with a 4 inch? Good luck. The 2 inch is way more nimble for bevels and cleaning up inside corners. For 3/4 plate, you're not taking off that much material at once anyway, so the bigger wheel doesn't save you time. It just adds weight and kills your wrists after a full day.
Man, that reminds me of trying to use a full-size chainsaw bar for pruning close to a house. It's just too much tool for the job, you're fighting it the whole time. I keep a little top-handle saw for that stuff now, way less tiring.
Ever think about how much extra sawdust you're making with the wrong tool? A big bar just throws chips everywhere when you're in close, makes a huge mess to clean up after. That time you spend cleaning could've been another cut with the right saw. Plus all that extra vibration from fighting a big saw just wears you out faster.