Mic for each instrument/vocalist can get good results but managing it all can get hairy fast, especially if you're also trying to do video. Do you have helpers? I've been doing audio and video a lot lately but I'm almost always by myself so I need to limit variables where I can.
Have you considered putting a stereo pair of cards in front of the group (think about ORTF config), and then get a soundboard feed into the same recorder and/or setup another pair of cardioid mics further in the room to provide the ambient/natural sound of being there that can be lost being up close?
You can then mix the three sources as makes sense in post processing and have a few options to choose from and experiment with. This might be an easier starting point than trying to mic up each performer individually.
^^^
All that.
First, let's make sure you are maximally leveraging the gear you already have.
Are you recording the soundboard (SBD) to one stereo input on your Tascam DR2d and a microphone pair placed out in the audience (AUD) to the other stereo input, then mixing those together in an appropriate way afterwards? If not, doing that may provide everything you are looking for and should be your next step.
The SBD feed will provide the clarity and proximity that you find lacking in your AUD pair alone. Recording a stereo output from the SBD is far easier to setup, and mix later, than attempting to close-mic all sources on stage yourself and record them separately. All that close-mic'ing setup work beforehand and mixing work afterwards has already been done for you in the form of the stereo SBD feed. Try to use that, and just add what's missing.
The AUD pair provides live audience ambiance, room sound, and stage sources not strongly included in the SBD intended for the PA. As long as you know you will have access to a good SBD feed, try using a pair of spaced omnis for your AUD mics instead of cardioids. The goal is to get from the AUD pair what you are
not getting from the SBD feed and vice-a-versa. The spaced omnis will actually sound
more distant than your AKG cardioid pair when listened to on their own, but that's not a problem because the SBD feed will be providing the clear-proximity stuff. The spaced omnis will do a better job of capturing all the stuff that's often not very well represented in the SBD if at all: the audience reaction, room sound, and the heavy bass stuff.
It's mostly about good teamwork between the AUD and the SBD pair. Managing those two audio sources while also doing video will be way, way easier than the much larger undertaking of trying to manage recording and mixing of a whole bunch of individual sources. Make sure you are getting the most of what you can do simply and effectively, before overly complicating things.