I have three C&V bikes, an Eddy Merckx 7-11 Corsa w/ DA 7400, a Zunow Z-1 w/ Sugino 75 road, and a Bridgestone RB-1 with Sante. all three have very different ride qualities.

the Merckx is by far the stiffest, and feel like a serious racing machine. It's not exactly a comfy ride but of all my bikes it feels like the one that demands and gets the best athletic performance from me.

the Zunow is a more comfortable ride, with curved chainstays and monostay. the only complaint I have is that Sugino 75 road group, while super rare and bling, doesn't deliver quite as smooth shifting as I would like. however the super-stiff crankset gives the bike a sporty edge.

the RB-1 is simply the best of the bunch. It's sized perfectly to me, is comfortable to ride but still aggressive and nimble. the Sante group is smoother than Dura Ace, and the Biopace chainrings give it a reassuring ease while climbing. it's the one I would keep over all the others - not as aggro as the Merckx or exotic as the Zunow, and not at all as collectible as either one, but all-around the best in terms of pure ride satisfaction.

so yeah, different tubing and designs deliver different rides. in terms of collectability, i think it's very hard to determine precisely. for someone who knows the more obscure, boutique Japanese handmade bikes, my Zunow is very rare and has an even more rare groupset. it took over a year to compile the parts group and would be very tough to replicate. but neither the bike nor the group would be very impressive to someone who prefers Italian design or parts.

the Merckx is the opposite - it's a nearly flawless example of an iconic and popular bike. however I see similar models pop up on eBay with surprising regularity. sure they typically pull $1500+ but if you have the cash you could have a Merckx like mine with relative ease.

and then you have the RB-1. another one of those cult bikes, and deserving of the high reputation. but unless you're a Bridgestone fanatic, it's probably "just another Japanese production bike" to you. *shrug*

anyway, collectability is driven by what's popularity and rarity. a rare but unpopular bike will command a lower price than a popular but more common bike.