I wouldn't do them, no matter what.
The reason is that the pullup is one of the few rare and valuable exercises where your spine is unloaded and you actively promote the muscles to counter bad posture under reasonable load.
You know, the behind the desk posture, the labourer's posture etc.
With BTN Pullup, you throw away practically the biggest (or second biggest, depending on personal training aim) advantage this exercise has to offer.
Apart from shoulder (which can be mostly avoided through being careful with the hang position) and tendonitis problems (which is more of a problem with very heavy external load and one arm chins), the chin up and the pull up are among the safest heavy exercises.
And since most other classic strength exercises are potentially a lot more dangerous (we're talking about going heavy with free weigths here), there is little sense in aggrevating the few ones who are kind on your joints.
Only someone with genuine bodybuilding or strength sport ambitions should try them out, in my opinion.