Cro-Mo is heavier than Hi-Ten but Cro-Mo is a hell of a lot stronger. I don't know much about teh Haro but the Sniper is an all right bike for a newbie. Another bike a might mention (not sure on the price) is the Redline 5-Spot. It is the mid range of the Redline Street bikes. The Peety Cash is the lower range and the C-Note is the Highest range. The 5-Spot frame is Tri-Moly with forged 5mm/7mm dropouts, the fork is full cro-mo, the cranks are cro-mo and and the pedals are alloy. If you can afford it (it is really that expensive compared to others) get the C-note. The frame is the same as the 5-Spot and the fork is 100% buttered cro-mo which is light and very strong. The cranks are the second best cranks redline make and are tubular 3-peice cro-mo, the ball bearings are sealed cartridge and the rims are one of the best rims in the street business. At least try and get the 5-Spot.
For more info:
www.redlinebicycles.com/home3.html
