Mercedes Benz E300 vs. E320

I just in the last few weeks finished completely restoring a 300E. It is completely flawless. I am in the process of marketing it, and would like to invest in another project car. I would appreciate some feed back as to whether the diesel is the better car or not? I am impressed with the statistics on the new 6 cylinder E320 CDI, but will the 1997 diesels compare with them or not? I know they will be more noisy, but are they a better investment in the long run over the Mercedes gas model for the same year? Thank you much, and the feed back in this forum has let me restore 2 mercedes' without even purchasing a repair manual. I am not for sure why Mercedes is the only one with this kind of forum!