I have heard this several times, just as often as "they are completely different." So, luckily, I found somebody who will lend me his PRO 2900 so I can do a side by side comparison. I will send him my PRO 900 first, though, so it won't be before at least another week.
I will create a new thread with a detailed comparison, as I have not yet written a full review of the PRO 900 (on English) yet. So in two weeks from now, I hope to bury this topic once and for all. Stay tuned!
* My impressions will be different to the others, as I think the PRO 900 are not musical at all - although they have great qualities! I also don't believe in cable magic, that silver pads sound much much better ("deeper bass"? Seriously?!) and I also think that amp-synergy is highly overrated. Prepare for a harsh, objective and down-to-earth review without any emotions/hype.