I can attest to the fact that it’s the quality and fit of the gauntlet that’s important, not the type. After some serious damage to my right thumb years ago, I ditched my ill-fitting clamshell gauntlets. These were the stereotypical, run of the mill, off the peg, gauntlets you see many SCAdians wearing. I opted to make my own faux finger gauntlets with enclosed thumbs patterned after photographs of Mad Matt’s and Anshelm Arms examples. My hands are protected to a much higher degree these days.
As Ian stated, sometimes it doesn’t matter what you’re wearing. An overzealous polearm blow that’s poorly blocked is going to hurt no matter what (as in my case). Well fitted armour does make a huge difference, but accidents do happen. We all play very rough games.