What I was riding was this and/or my single speed mud bike. I did race on the full suspension bike last season and the season before. It is a great racing bike. Especially for trails with a lot of rocks and roots to roll over, technical trail where you don't want to have to be very precise about the line you pick (if you hit a rock on that bike, it doesn't really matter, you'll just roll over it), and for learning to like some speed downhill. It is still VERY light for a full suspension bike and has some suspension dampening, so climbs better than most.
But...
I bought the full suspension bike when I was first getting back into mountain biking and I didn't really know where it was going to take me, so I got a bike that was reported to be a cross country bike but with enough of a slope to the head tube and enough suspension to handle technical, fast downhill riding. The blue bike did that. It allowed me to ride much more technical terraine than I would have been able to without the suspension and it really helped me learn how to pick lines around corners etc. And of course, everyone that was "serious" that I knew, had a full suspension bike so I got one too.
But full suspension is a PITA if it's muddy. It requires maintenance and takes a lot longer to clean up. Also, I have a tendency to avoid the pain of pushing a bigger gear and that was limiting my progress riding, especially hill climbing. So, the following winter, I took an old hard tail mountain bike and turned it into a single speed with a rigid fork for winter training. I discovered that my skills had progressed to the point that I could go downhill on the type of trails that I liked best (no big drops but some rocks and roots etc) without any significant loss of speed even though I didn't have any suspension. The bike was noticeably lighter when climbing and I liked that I didn't seem to be losing any of my effort going into the climb by the squishing of the suspension. As far as clean-up went, no problem, let the mud dry and brush it off easily in a few minutes, lube the chain and away you go again.
If I hadn't gotten the inkling to do this Portugal race, I would likely have just continued riding these two bikes and just picking the right days for them.
But my full suspension bike just is not appropriate for the Portugal race. It would not gain me anything on the descents with exception of a couple of Roman Road cobble descents which were very technical but are a miniscule part of the total mileage. The full suspension would be a disadvantage in terms of energy loss through the suspension on long flatter days and I would be doing my own maitenance in the evening and didn't want to have to worry about the suspension. The climbing that there is in this race can be very steep if not long, so any weight loss on the bike or me would also be helpful.
So this new bike is born for that race and is much better suited for the type of riding I am doing in general, which is tight twisty single track with lots of steep climbing but pretty buffed out trail for the most part. I had seriously contemplated building a hardtail, but I heard a lot of feedback from the racers (apart from my boyfriend who rides nothing but a fully rigid bike!) that having some rear suspension is really helpful in taking the edge off your butt, especially, over cobbles on long days. So I went with the pivotless rear suspension.
That's a really long answer to your question. But I didn't know how else to answer it without sounding vague. But really, I think that the bike you start riding on, is not the bike that you're likely to continue riding for a long time. Until you have some mountain biking experience, figure out what kind of riding you like and what your strengths and weaknesses are... you won't know what direction to go in. A good entry level full suspension bike is a good place to start. Then, maybe like me, you'll decide that you like the climbing and the challenge of long days in the saddle and you'll want a really light bike. Or, maybe you'll love ripping down hills, doing gap jumps or who knows what and you'll want a bike with HUGE suspension where weight is not a bad thing. Or maybe you'll just love all around riding and the jack of all trades bike will continue to be the right bike. Who knows where you'll end up, but enjoy the journey!!