A little bit of accuracy is nice to ensure you don’t miss. You can go full DEX if you’re using Sissel and that proc won’t be too terrible, so that is an option.
Most people go 200+ DEX because most people don’t test their attack speed by frames in on the training dummies to see if there are still benefits, and after you’ve already put the DEX in it’s hard to take it out without a stat potion which was previously only from events and/or a lot of medals, making it a difficult choice.
I’ve tested it on a few different characters, using xbow, kneeling and not (to try and find out how much +300 Attack Speed really is), mounted and not, on SR3 and my other character which have different DEX levels by far. (One is 422, the other is 160, I’ve also tried it on characters with around 50 since you can use cards to get a newbie at that level).
The difference can be pretty noticeable, but it’s never hitting the seemingly wild kToS levels of attack speed, I don’t feel I’m getting capped because at 400 I still see an increase, it’s just maybe not as much as someone would think if they weren’t measuring it themselves, have tested elsewhere too to make sure I’m still seeing that attack speed when there are things around to increase my ping to undesirable levels.