Yep. I was thinking in theory, but in practice, heise is very hard to get used to and to get fast. I use it sometimes, and most of the time is taken up by thinking about commutators.
But that's just me. Heise could be fast, it's just that so few people use it. I might actually take a week off roux and see how fast I can get with heise in a week (I'm like 40 seconds with heise but 16-18 seconds with roux so heise will improve quickly methinks- just have to get used to it).
For the moment, however, we don't know the future of heise. CFOP is in my opinion the most developed- what with the MGLS, ZBF2L, VH, you name it, Petrus a bit by Erik and others, Roux maybe by Thom (with his KCLL) and some others, and Heise- I don't even know any cuber who uses heise for speedsolving let alone being faster than me. So I guess the future for the less used methods is unknown...