I recently got the Spiral Dots, and I got to say, I like the slot for the iem sound tubing notch that keeps the tips in place. Although the fit is perfect with the ML size, the sound is pretty much the same as the silicon wide bore tips that comes with the iems that is more flabby in material than stiffer Spiral Dots silicones. What I've been using the whole time that sounded great to me was the KZ KS5 large star tips. They have a narrower bore than the Spiral Dots, but doesn't cover up the 3 sound outlets.
Spiral Dots on Left, and KZ ZS5 star tips on right for comparison(notice the bore size differences). Although the ZS5 star tips sound better to me, the problem it, it doesn't have notches to keep the tips in place when pulling out the iems. It's quite annoying having to pull the tips out of my ears every time. The widest bore does sound brighter in the lower treble area, and the star tips just sounds better, and I think it's the ideal bore diameter for non-narrow bore iems in general.