Looking at the angle of the ankle to the main boot they're moving further away from the traditional 3/4 season boot market the Manta previously dominated. When I say dominated, that's probably an understatement. From what I remember of the late 90s you couldn't talk about 3/4 season boots without the Manta being the dominant subject.
Yeah, they're a lot stiffer than they used to be. The SL now takes up that market, and so they've 'upgraded' the Manta, but you get the feeling some people haven't seen the change: I've seen people wearing them in the Lakes in summer on things like Skiddaw, where they're a little bit ott...
Regardless, that new boot looks ace - they should have had a rand previously and now they've done it.
I used a pair for winter trekking in North Africa. Warm enough for a day of mixed snow and ice, didn't use the GSB though as my crampons aren't compatible. Light enough to use for extended low level walk in without wishing for my 3-season boots!
I bought a new pair a few weeks ago as my old ones were 8-9 yrs old and showing a lot of wear. The old ones were also uncomfortable and always had been. I went up two sizes and wore them yesterday for a 12 mile low level yomp. Not a single hot spot or blister - result!
I think at the end of the day you wear the most comfortable boots for the occasion - I love my SL's and they are like slippers but, like yesterday, I wanted to break in a new pair of 3/4 season boots - so that's what I wore.
