3 points in riding is pretty nice to have, im level 32 with 9 power strike 1 ironflesh 5 ath 3 riding and 5 WM all in 2h
best part is with the build you have you can either go 2h cav or lancing, lancing isnt so bad on a champ rouncey with 3 riding if you have one, but 2h cav is a little trickier to pull off on a rouncey because they are pretty fragile and any aware melee player can take it down with 1-2 hits if you are going full speed
never tried a regular rouncey tho