Rega PPack plus 24v motor OR Ortofon 2M Blue?

As above, what would make a significant upgrade? I can avail both options on almost identical price level here in my country. I have the Rega RP1 and would like to improve the sound of the stock ortofon om5e cart. I would like a more rounded, meaty presentation as i find the entry level ortofon a bit lean especially on the bass front. I don't think a demo in one of the shops is ideal, given that it will be different to replicate the same sound once the chosen upgrade is set up at home. Will the Performance Pack consisting of the rega bias, white belt and table mat along with a new motor give me the results i want? Or a move to a more expensive cartridge such as the ortofon 2M blue be more feasable?