Am I right in thinking that SRAM shifters only work with SRAM mechs or this theory twaddle?

Your right for rear mechs; Shimano front mechs work with SRAM shifters though (my bike transmission is all SRAM apart from the SLX front mech; it all seems to work fine).

Andy

Numbered Sram stuff X0, X7 etc work only with Sram rear mechs. There are some out there, Rockets I think, that will work with Shimano rear mechs.

SRAM X-series use 1:1 ratio for rear mechs; Shimano use 1:2. This leaves Shimano rear derailleurs incompatible with SRAM shifters; and vice versa.

No such issue exists with the front derailleur, so shifters and derailleurs are interchangeable between manufacturers.

Also SRAM shifters which have names rather than numbers i.e. attack, rocket (rather than X7, X9) work with shimano rear mechs.

Edit: too slow.

what MrP said, I think – names(attack, rocket)=shimano, numbers/random letters (XO etc)=SRAM