Worked on that phone. I diagnosed if music player cache was working by putting back of phone to my ear and listening for seeking clicks from hdd
I had most of the N range, and was particularly interested in music ones, N95 was love/hate because the music button/reverse slide was so slow sometimes, and generally it just wasn't as good as N91 for music listening with its proper headphone jack placement, and always accessible controls.
What kind of magic did that HDD have that it could be thrown around like a phone typically is without the issues we would see if we'd handled a laptop with HDD the same way?
N91 also had a ridiculously high quality DAC that beat pants off iPods of that gen.
Sounds quality was great and I loved the dock too.