I ordered a couple of lambda test prints some weeks ago on DPII and Maxima, both in bright finish. Main difference was that Maxima had a noticiable higher brightness than DPII and it was also sharper (I don't know if it is really a paper feature). I didn't see any shadow detail increase but my image had very few shadow areas to evaluate it properly. Maxima print was a bit yellower than DPII print, but general saturation and contrast were similar on both. Paper weigths were also similar on my hands.
I ended up ordering the final print in DPII, Maxima brightness was a bit too much for me and I didn't see any clear advantage in my particular picture to pay the price premium of this paper.