I like the digestion damage increase, as in the grand scheme of things, it is still not all that much damage. The stomach isn't considered as a magical weapon, so if you aren't making the damage psychic as Fall is in his game, a lot of enemies will have resistance against the bludgeoning damage, if not the acid damage half of the gut. And of course, while there are feats, like great-weapon master which really boosts the damage of normal weapon attacks, there aren't really any so far to properly buff your digestion damage. So more feats could probably be warranted, though of course, nothing is stopping a player from asking their DM to design a new feat for what he/she wants to do.<br/><br/>Onto the goo-conundrum, I would leave it vague and up to the DM to decide how to handle it, as letting a player play a slime character would break a lot more things than just armour. After all, what would be stopping them from just squeezing in through a key-hole in a door to surpass it, or slip down through the cracks of a wooden flooring to the floor underneath. Personally though, I would have slime characters have lower base AC as well as gaining less of a benefit from armour, a small negative modifier to hit with manufactured weapons, but also resistance to non-magical slashing and piercing damage, while vulnerability to fire and lightning damage.