I'm not familiar with the Mandt System, so I just took a quick look at their site. I wouldn't consider it a credible system based on what I read. I worked in a place similar to where your wife works, and in my experience the prevention/defusion stage can't really be done with verbal redirection, at least the way it is usually taught. The staff really has to know the individual residents and the residents need to know the staff, just using verbal techniques taught in training won't work. I was usually successful, but only after I got to know the residents and they got to know me. Especially with one resident, a new staff was "Guy" until he knew his name, and as long as the staff was "Guy" he'd be attacked on almost every shift. Once he knew your name (and it took a while) he'd still frequently attack, but nowhere near as often.
I was taught a system called CIT (IIRC Client Intervention Techniques or maybe Completely Idiotic Techniques) which pretty much did not work. It might work for those in non-behavior houses.
I've never seen anyone successfully pull off any of their techniques. I heard of one guy who tried and got beat up. Most people resorted to wrestling.
I was able to technically do everything they taught and do it successfully only because of my training in Ninjutsu and FMA. Stupid hand techniques can work if you have good footwork and since the dopes who set up CIT did not take footwork into account they did not mandate bad footwork. A worthless release can work if you know how to take a person completly off balance by your footwork, and if you know how to move off the line of attack you don't have to rely on stupid blocks.
IMO it was much like the company's first aid and CPR training, just CYA for the company so they can claim their staff were trained. I was filling in at a non-violent house where a staff member was feeding a resident who started to choke. She just looked at me with wide eyes and said "He's choking" and froze up, and I used the Himelech and saved him. That was due to my Boy Scout training, they taught these skills more thoroughly than supposed professionals.
I only had to deal with a knife once, and it was a high-functional resident so I did rely highly on verbal redirection and backed up by my real skills to take the knife away. I have dealt with pens, pencils, and scissors on more occasions and basically used FMA trapping and disarming. To people who don't know FMA trapping looks like you are just putting your hands in the way of the attack.
I was never bitten, so I don't really know what will work in real life to stop a bite on yourself. The bites I stopped were against other residents. I also do pressure points differently than most people. I don't like the term because it seems to imply putting a little pressure on a point with your fingertips like you are pushing a button. What I do is use a knuckle and drive hard through the point as if I'm driving the person to the ground.
I was always able to get out of position of a bite. That starts with getting off line of the attack and if you fail at that, get out of any grab immediatly.
I'll give an example of the time I came very close to being bitten. A new resident was assigned to the house, and this was a really big guy. He was tall and bulky with a lot of muscle and he really liked to hit people. One of the staff was terrified of him and made sure he was in another room. I forgot whether he was my co-worker at the time or whether another equally useless staff was assigned to this shift. They hired too many ghetto idiots who did not do any work, and often paired them with productive staff so the work would still get done.
Anyway, I was taking one resident's blood pressure which had to be done every night. I was sitting down in a chair next to his. The big brute came up and hit this resident, and the resident immediatly attacked me. I had both my hands on the blood pressure cuff and was grabbed by the collar in the front. and pulled towards the resident for a bite. I stood up and fell back which took him off balance and quickly took my T-shirt off. Since he still had a grip on it. I got out of range and with me out of range he fixated on biting my T-shirt. I had claw cuts on my chest so I cleaned them with alcohol and dressed them and took out a new T-shirt from my bag. The first aid kit I carried in my bag was better than the Wal-Mart one the company used. I was concerned about an infection from the cuts but luckily I did not catch anything.
The shirt grab release taught in CIT was against someone grabbing a shirt at the side and having only a little bit of material in their fingers, not a full grab. Every shirt grab I saw at work was like the one that happened to me, a front collar grab where they get a whole handfull of the shirt and immediatly pull the victim towards their mouth.
I guess the lessons there are quickly removable shirts are useful, escaping techniques from martial arts work better than CIT escapes, and it is much better to have non-lazy staff. The guy I was working with should have stopped he big resident from attacking in the first place. Usually lazy staff just meant that others had to do their work, but in these types of incidents people could get killed while they are in another room listening to rap music.
The only CIT technique I've seen work (and have used myself) is the Basket Weave, but they don't teach an effective way to get into it.