Yea, to be quite honest, I'm more a believer in the "we're spending our time building a real product, we'll let you know when it's ready" approach compared to "and here's another beautiful piece of plastic that our marketing department things looks pretty sweet... what engineers? Yea, we asked them what the best components would be, but we didn't want them involved in the mock-ups... they always take the fun out of those things by demanding practical and producible results!".
lol that's just my take anyways ;o) In all seriousness, a mockup is a good step (especially if it's actually a proto-type with some good, serious effort behind it), but the difference between proto-type and finished product is usually quite large; and I'm not a big fan of sales pitches, so for me it's always who gets to the real, in your hand device that I can buy and use for my purposes first; all the rest of the bs in between is just to try and distract you from the time it takes to actually build a product from scratch.
(Btw, if you're that eager for mockups, I could throw together an RX-51 for you, no problemo... it probably has as much hope of resembling the final device and functionality as any other early stage mockup does! ;o) )