I wonder how this would influence the bonus rituals that a wizard receives throughout his or her career. If swapping Alchemy for Ritual Caster means a loss of those bonus rituals, even if the character takes ritual caster as a feat, then I don't think I would make this trade unless I had 0 interest in rituals. It seems better to pick up Alchemy as a feat and take Ritual Caster as a bonus class feature if you want to be able to do both.I like the idea of swapping Alchemy for Ritual Caster, for me I see Alchemy as being good from level 1 while Ritual Caster needs you to get levels in a far more substantive way.
I would much rather be making Alchemist's Fire than casting Comprehend Languages or Tenser's Floating Disk at first level. Rituals for me kick off at 5th level, so I'm more than happy to leave picking up Ritual Caster until level 4.