If I have Invisibility running and see a Pitbull, does it automatically fail to detect me, or do we still make opposed stealth/evasion rolls?
On the one hand, Invisibility says it "will allow the Netrunner to pass unnoticed through the Net." Plain reading: you're not detected. (Except by SeeYa, which specifically counters invisibility.)
On the other hand, that would mean that one of the least expensive (in cost and memory usage) programs moots all the defenses of any system not employing SeeYa. And why does Invisibility even need a strength, if not to pit against detection programs' strengths?