The manual says not to use the standard 13mm chuck with the SDS drill when
in hammer mode. What is the actual problem with doing this? A standard
chuck can cope with basic hammer drills - is it the heavier force from the
SDS drill that could be a problem?

Its just that I need to make a large hole through a wall for pipework and
have a 40cm x 20mm standard masonry drill bit but only a short 6" x 22mm SDS
drill bit. Just wondering whether I can make use of the longer non-SDS
drill bit in hammer mode in the standard chuck. What's the worst that can
happen?

Thanks

David