Hi Carlton,
No, you don't need that many. But you may find you
want that many, which is different, and less rational
I've been there, done that.
I'd consider one (or a combination) of these two approaches:
1. Exit Pupil
I've found that 2-3 eyepieces per scope pretty much covers what I
need (as opposed to
want) By exit pupil (EP focal length divided by scope f ratio), that would be:
one for the 0.5-1mm bracket
one for the 2-3mm bracket
one for the 4-5mm bracket.
Assuming you are happy to use your Powermate whenever needed (so aren't put of by the extra weight etc), the resulting number of EPs will not be all that many.
2. Experience with existing gear
The good news is that of your existing EPs, none are truly junk. Even the "least" favourable (the GSOs) are far from crappy, and all should be pretty darn good on-axis (centre of field). The bad news is that the main areas of performance gain by upgrading will therefore relate to off-axis-stuff like AFOV, coma correction, off-axis sharpness, distortion. On-axis, you are unlikely to gain over what you have already (if you insist, the best on-axis performers of all the EPs you list, are the TV Plössls IMHO). So find the EPs from your current lineup that give you the best views on-axis.
Once you have identifed the focal lengths that work best based on 1 or 2 above, you can decide what you'd like to improve off-axis (more AFOV, better edge performance, etc), and for ergonomics (mainly eye relief and eye placement), then go from there.
As a minimum, I'd be keeping the PM and the 6.7 Meade.