a mate of mine has recently decided he is going to buy a conversion kit, he has kept me in the loop while he's been "researching", he is far more thoughrough than myself.
for me, after the elation debarkel, i simply sent $500 off to china and got a front wheel 500w hub with 3 sealed gel 12v 10ah batteries (connected in series), it arrived fine, was very easy to install and worked immediately on my existing bike (and tag-along for my child), lately i upgraded the battery to a 36v p04 thingy from
www.solarbike.com.au which reduced the weight by 2/3rds, the initial battery did not work smoothly with my hub motor, and the proprietor of solarbike was fantastic, assisted me with all questions and eventually sent me a completely new battery with a controller that fixed the issue and my bike works like a dream (however i'm getting a little jealous with the system my friend is planning), he is dealing directly with
www.cyclone-usa.com and has sent through the responses to questions etc these guys also appear to be fantastic (the electronics are a tad over my head, but there are loads of sites out there offering various systems and parts, batteries etc)
i have another set of buddies that bought a system (again from usa, not sure through who though), they had just returned from europe and were inspired to get one of those large bikes with a huge storage area at the back two large pannier thingies with room for their two kids to sit on aswell, (the rear wheel and tyre is rated at over 200kg!), their bike is a custom built jobbie and has a an electric motor running the crank (if you wish i can find out who they used for that but i think the whole bike cost a bucket load)