Controllers: NTSC vs PAL?

Are Controllers/Mice/Keyboards compatible across UK and US consoles?

I think most controllers should be fine although some lightguns may have a problem.

only difference will be the blue swirl for european controllers in place of the red one for ntsc hardware.

Yep. Some guns won't work. I have a MadCatz Dream Blaster whilst a mate of mine has the offical sega gun both work fine with our PAL games (on PAL DC) but with the Japanese import of Death Crimson OX, only my gun works leaving the sega one incompatible.

Awesome. Thanks