Only had bad experiences with modern, plastic, link belts – both at home (Boxford CUD) and at work (J&S Cylindrical grinder). On the CUD a link belt has to be used, as it goes through the swarf tray to loop around the spindle. The original 1960s Boxford belt used a canvas based link, rather than the hard, shiny, fibre reinforced plastic links used today. Even bow-string tight the new belt slipped under load so, when I had to choose between a Super 7 & the CUD, the CUD went. Similar situation with the J & S grinder, which had 3 belts – we were recommended to use link belts for smooth running, but belt slip limited the load that could be applied (the machine had been converted into a CNC cut-off grinder to slice carbide tubes into short lengths for mechanical seals).
I much prefer raw edge, moulded cog wedge belts, as these conform well round small diameter pulleys, don't need to be excessively tight & drive well. I have no use for a power transmission system that doesn't transmit power when I need it to. Properly maintained (i.e. tensioned) endless belts last a long time, so the minor inconvenience of having to drop shafts or spindles out to change a belt is, to me, just that – a minor inconvenience.
Have not had much sucess with poly-vees in industrial applications either – but that is another can of worms !
Nigel B