I've been mountain biking for almost a year now, and I really love my bike (Trek Fuel EX 8)...I'm a big fan of the full suspension, as I feel like it has made it easier to learn/make mistakes without crashing every time...the suspension really seemed to make up for my lack of skill especially in the beginning...
That being said, I'm delving more into longer endurance racing, 60-100 miles, and with a lot of climbing...I'm finding the more I train on this bike, the more I feel like the squishiness is taking away some of my power on the long (4+ hr) endurance rides I've been doing...I love this bike for when I'm doing fun technical trails, with punchy/techy climbs and sweet descents, but long gravel roads it's definitely not built for

So, I'm looking into getting a 29er hardtail...I'm pretty tall (5'11") so have been inclined to a 29er all along, just all of the ones I wanted were sold out when I was purchasing my first bike...Now there are a few options I have available to me, and I'm just concerned about how much of a difference I would feel going from that rear suspension to a hardtail...am I going to feel like my rear is just bouncing all over the place? Sometimes I feel like I'm going to endo going downhill even with all of the suspension I have, and I'm worried it will be worse on a hardtail...though I think it will help my skills even more, and force me to pick better lines

Also, the bike I'm looking at (fingers crossed it's available) is the Salsa El Mariachi Ti...I've read and heard it's a standout bike, and perfect for long cross country races (Breck 100, LT 100, etc)

Does anyone have experience going from full suspension to hardtail, and also 26er to 29er?