had a cycleops magneto for 3 years now which adjusts its resistance, i think an excelent device.
however had a slight prob around xmas, emailed the importers paligap to see if it was something i could sort, and wihout a quibble they not only replaced the resitance unit but also upgraded me to a fluid 2.
the fluid is better again than the magneto, hate to repeat sales blurb but more 'road like' in the way the bike pedals and the resistance kicks in. also quiter, although the magneto is'nt really that noisy at all.
so anything by cycleops would be my call, great kit backed up by superb customer servce.