I have a pair of wading sandals (made by Keen and designed for water sports) to which I added a few metal studs and have been using for wet wading while fly fishing in shallow streams. Now I wonder if I can use them with proper waders in lieu of wading boot or wading shoes (i.e. wear the sandals over the neoprene 'socks' of the waders). Is there anyone there who has tried it? Are there any disadvantages or problems that would make it impractical? I currently don't own waders, so I can't test it myself.
I would hesitate to do so. The keen wading sandals I've worn let in a fair amount of gravel. This gravel, when caught between the sandal and the neoprene bootie, will make mincemeat of the bootie - causing it to leak.
Gravel is a concern even when using full-on wading boots. To combat this many waders have gaiters built in. Mine do not, but I purchased neoprene gaiters to help keep gravel out.
That said, I have use an old pair of high-tops over my neoprene booties - with the gaiter. Works just fine as long as the traction is up to the job.