I'm a competitive runner who focuses mostly on ultra marathons, and I also work at a speciality running shop, so let's see if I can help at all. =] Minimalist shoes can definitely be beneficial if used properly, meaning that you transition into them slowly. I used to run in a more traditional, built up shoe, but I found that after switching to more of a "barefoot" shoe my efficiency improved, as well as my leg strength. You're going to be working a lot more muscles in your calves, shins, feet, etc. that aren't normally used, so it's important to be patient when first wearing these types of shoes.
I'm guessing the NB shoes you're talking about are the Minimus? If so, I absolutely love this shoe...I have 3 pairs =] It's great because it has a bit of a heel (as compared to a Vibram Five Finger, which has none) so it won't stress your calves as much...it also has a tiny bit more cushion which is helpful. However, I will say that after taking a 7 week break from running (got injured while training for Vermont 100) I just recently started running again in the Minimus and my calves are wrecked. After so much down time, I simply have to readjust to the shoes. Also, minimalist shoes are great for gym workouts because they put you closer to the ground, which generally gives you a little more stability (they won't help with over-pronation though).
Hope I helped!
I got Vibrams for xmas last year and they are really fun and feel great. I did run in them a few times and liked the experience. I also recommend going sloowwww with the transition. (I did get a few blisters at first running in them). I now mostly run in Brooks Green Silence. The Brooks are less built up than regular shoes but more than barefoot ones. I also know a guy that swore by his Luna barefoot running sandals.. Good luck!
My first day training barefoot was a couple years back when marathon training was life...I ended up stepping on the short end of a golf tee and hobbling down to 3RO (the closest thing to a running specialty shop we have for now) and picking up a pair of VFFs. I'd love to say I haven't looked back, but that would be a lie. It was a bit too much of a jump from the mizuno wave rider's I had been running in, and I ended up wishing I had been born without calves, not to mention the foot pain that comes with feet which have been babied in cushioned, supported shoes for their first couple decades of life. The minimus from NB are an amazing shoe, plus Anton Krupicka sports them :) Not to put the barefoot movement on a pedestal...but I wouldn't be surprised if your knee tendonitis disappeared with the decrease in heel lift. I'm just one person, but it definitely took care of tons of aches and pains for me, probably along with the transition to longer distance trail running...what kind of running are you doing? Keep me posted on your purchases and progress, it's always great to hear from someone else's point of view :D
I have run in several minimalist shoes: watersox ($10 from Sports Authority), Luna sandals, Merrell Trail Gloves, and currently Saucony Hattoris. The Hattoris are my favorites by far. They are very comfortable, and I love the Velcro so I don't have to tie them. I also occasionally run barefoot, but not for long distances.
I don't know about your knee or ankle situation. And it seems that professionals often given conflicting advice about what to do, whether to use orthotics, etc. Maybe try some minimalist shoes and see how your body reacts. I do think it's good to avoid heel striking. The Pose and Chi Running methods both talk about this.
*BUMP* I'm glad I found this thread. It's quite helpful! :)
+1 the Chi recommendation above.
Having both studied and practice real barefooting and minimalist shoe running, I believe it's important to practice fully bare running first, gently and progressively before trying minimalist kicks. The main reason is that it is only by being completely bare (on our feet!) that we are able to hone a safe technique. And a bare sole will keep initial distances honest. Minimalist shoes, while wonderful under appropriate usage and form, simply retard body feedback too much for those still learning basic techniques. And yes, there is a learning curve. Some fine resources I recommend are Michael Sandler's "Barefoot Running" (runbare.com)
and Ken Bob's "Barefootrunning: Step by Step."