If your app can run with just the h/w (CPU,Disk,RAM) available @ D-O you can do the migration. AFAIK, D-O does not have EBS like storage, which is essential in case there is lot of data that needs to be stored.
I have couple of sites (pretty low traffic) [nodejs, hhvm] running on D-O with pretty good uptime (> 1 year)
I'd recommend you to jot things down w.r.t what all things you have in terms of CPU, Disk, Memory, Apps, Server Usage over a week/month/year period and then see if the instances @ D-O can help.
Also, plan for future growth of the App, Just in case there is a sudden spike in traffic, there might be sudden need for additional Storage. In such scenario, with D-O you need to buy new servers, with EC2 you can add another disk with ease and can scale on storage.
AFAIK, D-O does not have ELB, so we need to buy instances and run ATS, Nginx, HAproxy, etc to do the load-balancing