honestly not the dumbest idea ive heard, but id be nervous about side loads and shock loads breaking vacuum at the worst possible time. for light duty maybe, but for actual vise abuse id probably trust some kind of mechanical floor lock a lot more than suction alone.
thats a nice piece, real clean lines on it and the grind looks pretty even from the pics. shape looks like itd split decent without being some goofy overbuilt mall ninja thing. old kelly works stuff always has more character than most of the new junk too.
yeah i still use em, not my first grab but theyre handy when you need more contact and dont feel like rounding off some crusty fastener with 12 point junk