If I were you and had time/money all accounted for I would do this:
1) I-PAC2, Opti-PAC, MAME Driving specific. Try to make your SW yoke swappable for this too. (explain later)
2)I-PAC4, MAME Dedicated 4 player (gauntlet, TMNT, D&D...)
3)I-PAC2, MAME Generic. This would be the beast. Fighting games, general stuff (not 70's/early 80's). 2 8-ways and 8 buttons each or so.
4)I-PAC2, MAME Classic Game dedicated. 1 4-way, trackball, spinner, maybe a tron stick.
5)Sell to a collector for putting Andy into retirement from all your I-PAC purchases.
Again, what I would do if I had the $$$ and the nice stuff you have. Good luck!
D-