My problem with HTTPS is Google: They push it on every front, but - for various reasons - consider HTTPS and HTTP different pages, meaning you do not get link juice from any HTTP links if you're site is HTTPS only.

(1. don't listen to people telling you otherwise, it's an expensive experiment 2. redirects do not transfer all the juice, they count as links themselves, from my experience it's like not having external links to your site at all 3. If you do not depend on Google b/c you're SaaS, go for HTTPS only)