a 530X in most bikes is about like dropping a V8 in a Geo Metro. Fun, but overkill.
there aren't many truly waterproof motors out there yet, but they are coming online with more resistant ones, like the newer generation of Crystalytes and the Nine Cont. motors.
As for what to recommend, that's hard to do without knowing a little more about what you want.
Do you:...
-Want immediate start, or something that you have to pedal first before you can use the motor?
Me: Pedal assist is fine for me. I like the idea of getting some exercise on my commutes and still not be sweating like a hog when I get to work or school.
-Rocket like acceleration, or something closer to a bicycle?
Me: bicycle type, I'm not looking to race, just commute.
-Silent operation, or is some motor noise acceptable?
Me: Not a concern to me, silent or some noise, whatever.
--How about if the best choice also sounded like a drill on steroids?
Me: I have worked construction, but this might be too noisy for me.
-Care more about weight, or range?
Me: both are a concern for me. I consider that I will have to pedal the added weight if the system fails on me while traveling. Looking for about a 10 - 15 mile range. I can recharge while at work.
-Stealth? As in, is it ok if it looks like a kid's science project, or would you prefer no one can tell?
Me: Test tubes? Tesla coils? Spark gaps...sounds cool to me.
-Do you have a preference for where you carry the weight on the bike?
Me: My EZ-1 is a long wheel base bike, I should be able to put the weight anywhere.
-What range are you looking for? Me: 10-15 miles
-What speed will you be cruising at most?
Me: Law allows up to 20 mph without licensing.
-Whats your budget?
Me: Depends on the system. I hope to start in the $500 range with sla batteries and upgrade to lipofe later
-Whats your skill level at turning wrenches and splicing wires?
Me: Highlty skilled elelctrician and mechanic...give me the parts and I can make it work.