YES. Schaller straplocks are the only thing all my guitars have in common. They're great. With the strap off they look like ordinary strap buttons, perhaps a little more rounded. The strap gets a horseshoe-shaped steel "foot" attached to it with a washer and nut. On the nut side there's a steel pin that you have to pull up on, or the horseshoe won't slide off the peg. It's a great design and it's a true "lock", unlike some POS's that are advertised as straplocks.
Schaller straplocks: $12. Not having to worry about dropping your guitar: priceless.
There are a handful of drawbacks, none of them dealbreakers:
- I have to take off the strap to put my strat in its case. It won't fit otherwise, because the whole peg-horsehoe-pin assembly is fairly bulky.
- On a related note (not relevant to Warmoths), access to frets near the heel on an acoustic is kind of difficult with the strap on, again because the straplock is bulky.
- If you're sitting and have the strap hanging slack around your neck, the straplocks can vibrate while you play. Doesn't matter if you're plugged in, but it can be annoying if you're playing acoustic.
All of these problems are solved by taking the strap off, and you can still put a regular strap on the straplock buttons... not as secure as a normal peg but I guess it'll work OK. (Um... disclaimer: I take no responsibility if you put a regular strap on your straplock pegs and break your guitar.)
Long story short, get straplocks, you won't regret it. And if you do you can just put back your original pegs.
Edit: No they don't affect the balance.