What are the negatives of using a capacitor with a lower rating than than your total system power?

Example, let's say I am currently running about 800 watts (rms) and using a 1 farad cap and was thinking about upgrading one of the amps bringing my total watts in rms to about 1500. What kind of issues might I run into? If upgrading caps should I go with 1.5 or 2 farads ? Is it a bad idea to (overcapacitate)? I know caps are just energy storage but aren't their ratings subject to intervals of use? Say, what if in my daily commute I consistently listened to the stereo at 3/4 volume and my commute changed from 30 minutes to 90 minutes. Isn't this a factor?