Hi lad
I am saying that everybody states things about alluminium based just on theory. A 1999-2003 frame with new alloy mixes hasnt passed the test of time yet, am i correct? you cannot prejudge a material before the test of time. I am part mathematician part aerospace engineer and i know bits about materials. Alluminium is a crap metal as raw material...but its very very good if treated and mixed properly as it is today eg. audi aluminium car bodies etc. Steel is very good but it is also non lasting...since corrosion is a big issue especially for mtbs . The only everlasting material is Ti but then again its better to buy 4 bikes made by allu than a Ti one that will last for 30 years.... plus it will cost you less.
ps. Are you happy with the rockhopper?