hi spidey
i've been using primare amps for the last 9 years and can shed some light on your original query. do keep in mind however, that my views are merely a subjective opinion. ultimately, you should trust your own ears. anyway, here goes:
current setup: ca 840c > primare i30 > epos m22
cdp and amp running balanced via mogami gold studio xlrs
m22s tri-wired with qed silver xt
room: 26' x 18' x 9'
regarding reliability: the i30 has been working flawlessly for the last 2 years. prior to that, the i20 served me well for 7 ears without a hiccup.
regarding sound: excellent detail and clarity, huge soundstage, deep well-controlled bass, superb timing. above all else, i find this amp lets the music through with very little (if anything) added to it. any change in source component or speakers is immediately apparent.
regarding cost: i paid 1.3 for mine 2 years ago. however, when the time comes, i doubt i'd be willing to part with mine for 50k!
the logic i would apply for pricing is this: what can the buyer get NEW that sounds nearly as good? the simple answer: for under 75k, very little.
hope that helps.
cheers
coaltrain