I don't play many 15 int characters, but I do play a lot of 16 int characters. Maybe the drop off from 16 to 15 int matters some, but nothing THAT drastic, especially not with saves that high.
As any number of duergar warriors, any time I had more than ~50 svs sans warcry I was only worried about maybe one or two pure spellcasters in the mud. Now...once you start getting low on con, that's another story entirely...
Now maybe a spam sleep artist managed to get you a few times, but once you're slept a lot of the maledicts are con checks anyway.