I've just had this conversation in another thread but Welsh ponies and horses have dipped backs, it in their breeding and it is most definitely not a conformation fault.
Look for the thread in PG about the section A William (sorry, cant remember owners username) - Welshes naturally have that kind of shape - spooks is exactly the same - it is not a horrendous fault (as some would have you believe
)
Hw is lovely and the second set of piccies show him off brilliantly!
Why not settle for the best of both worlds and break him to ride and drive - I am sure he would love it all!