Re: What is more reliable?
I'd have to suggest a moped as well. If it is yer buddy's first motorized bicycle build and under $500, gonna be some lessons learned and some part failures. For cummuting and when you absolutly need em, thats when things go wrong. Is a law or some thing. Also, with that long a ride every day, full suspension is almost a most. Especially for a larger person. Lights and a horn are really great things that would need to be added for safety. (opptional)
Adding to build costs.
All around and IMVH, a moped is designed for this. Where a bicycle with a motor is more then capible but I think a moped is much better suited.
Just a thought.