I actually started doing A LOT better when I switched to
Bovada and knew not only were HUDS less useful there but also note taking was less useful. I take notes on players sometimes in MTTs but in cash games (and zone poker) its pretty useless for me. I did try a HUD on sites like BCP but found it distracted rather than aided me.
I think part of that is because it's easier to use a basic strategy to profit on a site without names and less HUD use. Which allows you to change up your game and try different things.
Also live play doesn't have a HUD so what do online players do when faced with live play and no HUDS?
I'm anti-HUD to the extent that I think it dilutes the fun and value of the game for recreational players. It is also super exploitable. If I know you're a HUD user I'm going to mix play up a lot, jump around tables, switch up betting patterns, and do a lot to give your stats tracker on me the wrong information. I think it takes away core aspects of the game. I think esp for newer players it gives a false sense of relying on data that may or may not be usable in a given situation and they miss core information because they're so focused on either their own stats or the villain's stats. I cringe when I see posts like "my VPIP and PR% vs. XYZ% +/- cats/pre flop *42 is good or no? Can I fix it?" because to me that's not poker and if you get into the game thinking HUD data is the secret to success you lose sight of the actual game you're playing.
That said I think if I was multi tabling 16 tables then yes using a HUD and learning what the stats mean would be helpful in making decisions quickly and without much thought.
Overall I think the real danger with HUDs is that you could become so reliant on them that you miss key information or you get into bad playing habits because you're playing based on past data and not the current hand.