the mk1 haldex with standard controller only puts power to the rear when there is 15 degrees of slip on the front wheels i believe, the blue(upgraded) controller cuts in earlier as it will cut in when WOT below certain speeds whilst putting more power to the rear and more aggressively, it makes a nice difference(I have it on my octavia).
the mk1 haldex cannot go 4wd when stationary due to how it works, the mk2 haldex can go 4wd without movement though but requires a different ecu to the mk1.
its lucky you changed back to haldex as the gearboxes for haldex equipped cars don't have centre diffs in them as its part of the rear diff, I think the rallye gearbox had the centre diff in the transfer box.