When push comes to shove, performance brake fluid will be more likely to save your butt then stainless steel lines. If you're flying down a backcountry road, and your pedal suddenly sinks to the floor, it's not going to be because of the lines (and if it is, you're screwed with or without stainless crap).
ATE is $10 a liter (at least in the states), and if you're smart about it, a liter is all you need to flush your system. Heck, at worst, you'll spend $20. Skip the trip to McD's 4 times a week, and you just bought yourself some high perf. fluid!!