Conclusion:

The results of the experiments show a clear advantage to adding capacitors to an AEG mechbox. The associated gain in rate of fire is advantageous from a tactical standpoint, and comes at minimal expense. Causual browsing of the capacitors available for purchase at DigiKey.com reveals that many are reasonably affordable and exhibit statistics suitable for use with an AEG. If you are handy with a soldering iron and don't mind some electrical wiring, adding capacitors to your AEG is a worthwhile endeavor.