Hit with dispel magic AC goes from potentially 28 to 23 with Shield. Nothing to sneeze at at level 9. Plus there is always Counterspell if reaction still available. As soon as +1 Studded Leather is found then the Mage Armor issue is negated and AC only drops to 26 with Shield. I don't see Dispel Magic as a Hero to Zero issue.I guess your DM doesn't use dispel magic alot.
This PC could go from hero to zero very quickly.