I agree with you, on some satellites, the difference of resolution between pan and multispectral becomes ridiculous. Keep in mind that a ration 1:4 means you get 16 Pan pixels for one multispectral ! High contrast objects completely "smear" on the neighbours. I understand for marketing reasons, producers want to announce the highest figures, but....
I'm not even talking about the effective resolution of these images. If you want, you can resample a Landsat TM image to 10 cm !
I don't thin an algorithm will be able to reconstruct high res multispectral images suitable with classification. If the information is not there, you will never reconstruct it. On the same mood, you could also publish a movie captured with your cell phone on a Blu-Ray disc. It's feasible, but the results...
If your classification is mainly based on spectral properties (e.g. agriculture), I will rather work on pure spectral bands only.
If recognition is more based on shape and structure, Pan-sharpening may help.
I would rather use pan sharpened images for visual interpretation only.