You mean the Nimbus Delta S and Nimbus Delta V? I think a youth player uses Nimbus Delta S on FH, and I've hit a few balls with it (and I've been playing Rozena for over half a year now).
Nimbus Delta S is softer than Rozena. I think they are comparable in speed. Rozena is less spin-sensitive. I got spinnier serves with Nimbus Delta S, but spinnier short pushes with Rozena. Opening up on high back spin, I estimate the spin level to be substantially higher with NDS. However, when counterspinning my impression is that a good hit with Rozena results in a slightly higher quality -- tons of spin, more pressure depthwise -- with about equal speed.
Durability, well, what can one say based upon subjective judgements based in anecdotal evidence of sample size 1? My Rozena's, which are played for 10-14 hrs/week, cleaned gently after play, covered, and stored in room temperature and humidity, are holding up find. The red rubbers is discoloring where my index finger rests, and has minor edge crumbles. I think the young player using that NDS is using it for over half a year, and it seems slightly degraded in spin, has lost some of its kick, but still plays very well.