The canti brakes should be fine - invest a coupla bucks in
good brake pads (true with any brake design btw) and yer golden
Just make sure you have front brakes at least lol
Having said that - if you can easily afford it get the slightly better bike. While many build on the $100 and less el'cheapos with great success, it doesn't hurt to have slightly better equipment. Of course you can always upgrade things too.
When I was shoppin' for cheap bikes, I looked at the $100 - $200 range and I noticed that the $200 ones were often better built and with nicer equipment, so I sprung the "big bucks" for the $200 cheapo...
*shrug* your call - you'll love it no matter what bike ya get lol
Come to think on it - have you looked for a quality
used bike in that range? You might score an awesome one for the money.