I gave you the hint on the HD because of what you said, you want light but strong, you want to climb well but flow down with no problems. Taking the two choices you gave (Nomad and 575 - I own a 575) the Nomad seems more like the bike you want. But if you really want the blend of light weight and strengh, the new HD looks like the new winner. I also have a Mojo SL, and damn, it's good. The DW link is somewhat surprising. If you try bounce it down by pressing over the shock, you won't see much of a movement, it moves slightly down, and while pedaling you don't feel like you are on a jumping bed. But jump, or take a big hit and you will fell the suspension swallowing that, like if it had an inch more of travel. Plus, I don't know what are the stiffness issues people usually report here, I never felt that, so reganding this then, my 575 is a wet noodle compared to the Mojo. So, when the HD showed up, it really made me think about this new type of bike, an evolved AM bike, a bike with less than 27 lbs and 160mm front and rear.
Yodi is right about the difference on geo numbers and travel for trail and AM bikes, because you have to learn to ride with 160mm of travel and a slacker HT angle, it is very different - but only if you are a XC rider; if you ride bikes with 5+ inches already, you are more likely to enjoy having more travel than hate it. I love long travel bikes and I love the way they feel. I hate stiff suspension bikes as hell, I'd rather be on HTs, so I have HTs and long travel bikes, nothing in between. I once had the chance to ride a Ransom LTD, barely over 30lbs. That was amazing. The trails I ride were something else, I never felt so free over a bike like I felt that day. I felt like Superman. But take on climbs was different. Not worse, only different. You simply can't get on the pedals and smash it, it will do no good and you will fade in no time. So, I guess I can take one little compromise when climbing for a perfect ride everywhere else.
But now the Mojo HD, with its DW link system, I guess it will simply make that long climbs way less compromising than on any other lightweiht long travel bike. Taking on climbs with the 575 is just fun and fairly easy, considering it's 2pounds heavier than the SL, has a bit more travel and a longer wheelbase, all combined with the ASR single-pivot. But the Mojo simply climbs better and has a more effective suspension work when going downhill, period. Considering all that, the Mojo HD seems like the perfect bike. At least for me. More yet if you think that a regular Mojo will have near the same HT and ST angles as the HD with the same forks (68ºHT for 150mm forks and 67ºHT for 160mm forks - the 69ºHT mark is for 140mm forks), what makes the HD even more interesting.