A1094: RAW is murky in this case, the feat states you get the subtypes when you are in said race form and you can't be in elf and Dwarf form at the same time. On the other hand, ToB lacks the the rule that states you loose your class abilities if you cease to meet the pre-requisites and it is generally assumed you only need to meet the Pre-requisites during the leveling up so it could be argued that you could get both classes benefits.