No doubt that rotars can produce great results, one of my mates has a Series 3 RX-7 with a 13b that runs low 11's, cost him like $12,000 or something ridiculous, but when you turn around and find out he's spent $80 in fuel, one night cruising, it makes you think.
Have you ever seen a rotary drag meeting though ? Like the Jamboree ? The amount of stoppage time due to oil on the track is a bitch, oh yeah, my mates also selling his car cause he's sick of all the money and time it keeps to maintain it.
Although on the plus side, the Series 6 is definately a dead sexy car, great performance package, but as far as any sense of practicality goes, i don't know.