I have spent some time wearing the TLD Stage Helmet...
I measure at the bigger side of Large according to their sizing chart.
When fitting the helmet dry, I used the large insert for the helmet cushion that connects to the MIPS system, 15mm cheek and neck cushions. This was the best fit when the hemet was dry.
When the hemet got wet, it did not feel any heavier. However, it did loosen up on me. I swapped back to the medium insert, 35mm neck and cheek pads... too tight...
I found the perfect fit when the helmet is wet is with the Medium padding on the MIPS, 15mm neck pad and 25mm cheek pads. Its a tight fit when the helmet is dry but gives a couple mm when wet and fits really nice and very comfortable wet.
It does not restrict periphial vision at all and moves very little in wipeouts.
The MIPS is pretty neat. It allows the helmet to shift around a little. I did find that when I first used the helmet and it was a bit too loose, I pulled one of the elastic hooks from the cage that the padding attaches to. I was constantly readjusting the helmet when it was too loose (lots of wiping out) but once I got the fit right, there has been very little readjusting after wipeouts.
This is my first helmet for any watersport so, I do not have anything to compare to... but I am very satisfied with the helmet.