When pika got a python3 compatible version, we ran out of excuses to not use python3, but still my colleague was worried that "it would take too long to port things, and our-code-is-working-so-why-bother". I decided to try it anyway, and it took me less than a lazy Friday afternoon to run 2to3 on all the packages and get the tests to pass.
Given that your work is with scientific computing and (presumably?) you have control over the deployment environments, I'd really recommend that you avoid do the switch sooner than later.
I stuck with that line, because maybe his colleagues are also waiting for "50% of colleagues using Py3" and it's just a deadlock until some few brave enough starts to port and tip the balance.
Python 3 also has a load of improvements that would make scientific programming faster.
Perhaps instead of thinking about not having spare time to port your code, that you're saving time for future you by not creating more work to port over when you end up really needing that mind blowing new library :)