Took the '13 Skyhook out for a spin. Spent about an hour on mixed roads and speeds and I think I got a pretty good impression.
The overall difference between my standard Marzocchi 2012 and the Skyhook is, I would say, subtle (and not necessarily for the better). But before I get to that, I'll talk about the modes.
I haven't ridden the Ohlins version so this was my first experience on the changeable modes. The difference between Sport and Urban, for example, is significant and you're definitely getting a different bike (the engine mappings are also on my standard so this wasn't new to me). Personally, if I owned this bike I would program it to have the engine sport mode with the urban suspension setting. It is wonderfully plush and controlled and comes closest to the feeling of the standard bike.
The sport mode just didn't work for me. It's choppy and not comfortable at all and would wear me out on my daily commute in no time. I run my 'Strada in the engine sport mode pretty much exclusively and love the responsiveness and the suspension seems calibrated to work well with it, I never wish for stiffer settings.
Talking of the engine, the twin plug is maybe an improvement (perhaps a little smoother on throttle transition off the bottom) but there's still the hint of lean hunting on steady throttle. As mine doesn't have any of the issues I've read about on earlier models this isn't a big deal for me. The '13 is still a big lumpy performance twin (it hasn't morphed into a 1050 Tiger) and you'll know if that's something you can live with or not.
When I got back on mine it did remind me how great the standard bike is. I think it's a wonder what they've done with that suspension. This might be a false impression but I felt the '13 was squatting much more than mine but perhaps the sag was way off
If you already own a standard or Ohlins version, particularly the '12 model, I don't think you have anything to regret. If you love your currrent Mutly the Skyhook doesn't seem that big of a difference. If you're in the market for a new Multistrada the Skyhook is going to be fine - the bike still has all the attributes that make it great.