I've never used Paxum, but dwolla charges $0.25 for each transfer. Though still cheaper than Mt Gox in many cases, for someone selling .1BTC, it would be a large fee. If they (or any other funding option) have an issue regarding the frequency of transactions, this may not be a viable option for a day-trader, esp. a HFT bot.

This  does give an easy straight forward means of getting money in to BTC for the average Joe just trying to make a quick purchase though.

Good Luck with your project.