I don't know a lot about the Crusades. I did a bit of research into the why they started in the first place but honestly I think humanity has gone through a few Crusades even since the one mentioned here began. Humanity does interesting things, sometimes for ideals and sometimes that is simply the excuse.
I don't think you can say any one group is over-rated per se, I am sure some of them honestly believed in what they were doing and why they were there. However I am also sure that others were using the group to put a holy light on theft, murder, and a host of other things that were less savor.
I think the Hospitalers are a fine group to take up kit for.
Of course this coming from someone who knows little about them. I think it is time for research, oh yes I do.