I use the DW ones (plus a front anchor) on my 1970's Slingerland and they work great. I get zero creep now and I'm very heavy footed.The DW clamp on spurs are probably the best. About $70. Danmar's are a bit more retro, cost about $40 ..... but don't work as well. And if what you've got are true vintage clamp ons ...... I feel your pain
You soon get used to getting them setup quickly and correctly, with regards to what other posters have said about them.