If you don't mind some criticism..
nope, provided it is within my control
These shots are a good starting point but it seems your subjects torsos and anything that is not skin get lost in the background. I would suggest maybe finding a part of the background that is lit differently to pull your subjects out. they are also a bit on the cooler side of wb. it also may be nice to get shots from another angle.
Well, I would disagree as far as getting lost in the background. Background (as the word implies) is not as important as the subject matter (foreground). Wish I had time to pose these legends so they could have stood away from the blocking mike stands or off to the right where there was a stage door but sadly that wasn't an option. This was at a major concert hall, not a pub. They also didn't move around much as both Colin and Dave are 71 years old. Dave Cousins sat in that chair during the Strawbs entire performance. Colin (from the Zombies)was flanked by his keyboardist Rod Argent (Argent) and his guitarist as well as bassist Jim Rodford (Kinks). There were mike stands, cables and other things that would have made the shots more distracting with respect to background. Easy for me on this monitor to distinguish not sure on your end ?? Bear in mind, No flash is allowed in this club that takes care of that and all I had to work with was the over head lights. Whatever they lit up at the time of the photo is what I had available (and those were the best as red, green and blue where the other stage light options). Did you notice how both artists had on dark / black clothing? Not much of an option there as well..again dealing only with the club lights (no control). Perhaps in Post with the RAW I could have deselected AWB or As Shot and went with a Tungsten light or Color Temp though that would have made the photo look less than how it originally appeared. I did bring a WhiBal Pro white balance 18% gray card for White correction so what you see is matched with that card. (note EXIF is listed "custom" for white balance.) The club was literally jammed. They escort you back to your seat if your not seated and chairs were blocking both sides of the stage. Had to stand back near the men's room just to pop these out. I've been shooting pics since the late 70s and video since the early 80s so I am aware of moving around and getting different angles. I climb, lay on the ground, step on chairs etc all for the unusual perspective..when accessible (I even trespass at times

Unfortunately this was the only good place.
If your using auto iso then you may as well be using Av or Tv. I personally never trust auto iso, although that is just preference. I also wouldn't be too afraid of reds and stronger colors as you can use them as an effect in your shots when handled properly in framing and exposure.
Not a big fan of reds interfering with closeup shots as these but that's just my preference..I simply don't like the look "as much" unless I'm going to convert to B&W that that creates a whole new scenario. The reason I chose AUTO ISO is due to the unpredictablility of the light as it changes moment by moment. It's not like I am outdoors for an hour where the lighting is consistent or if a flash was available. Sometimes the vocalist had one light, 5 lights 3 lights, flashing lights, shadowy light..auto ISO was the best option as I was more concerned with over or under exposures occurring. In film days at indoor shows I'd almost always pick ISO 1000 and was fairly successful but why go that high if not necessary. I'd rather have the camera intelligently auto negotiate at say 800 vs. a steady 1000 and get inconsistency which allows me to focus more on the shot than the mechanics.
For the shots that are slower than 100th/s i make sure to take anywhere from 2-4 shots in burst of the same shot to helps my chances of getting the shots.
Just my 2 cents. =-)
yes I would agree with this and did take quite a few but perhaps could have taken more. You would have had to been at this show to understand the surroundings and how to work with them (I will spare the elaboration). Thanks for the offering of tips..though I am not sure your style and my style overlap at all. Not a big fan of shadows or mikes in peoples faces, excessive lens flare or photos swaying too far away from the subject matter that the subject gets convoluted..again that's just my preference you have your own style which makes us all unique. That's my two cents.