Good points!

I think you should buy the bike that looks the best and ride by yourself with no computer. That way you will be able to imagine yourself going faster and tell everyone how great you are! (I have debated on doing this myself) :)

Seriously you do have some great concerns, but as Tom Demerly said, find someone in your area that has helped many people reach their goals and has a great reputation on doing what is right, not someone who has had someone sell them a product.

Good Luck!