Honestly I personally think the only downside is it is more expensive. I personally would be just as happy with route 3 than I would route 1 since I think the ATPL is arguably better than MPL, with regards to job security, since other airlines seem to still prefer it. Thats not to say the the MPL isn't good too though.
Of course this is just my opinion.
Congratulations by the way! I've got my Stage 2 on the 26th so I am a long way off knowing anything.