Aside from the bike being C&V, this might actually have been an answer better suited to the Road Forums, although, since you're asking about whether it'll hold up or not, I guess it would just bring it back here. Well, quick search tells me you've got Tripled Butted Cro-mo Manganese tubing, which some people like, and some people hate (some people have said that it has a lifeless feel), I personally, have no experience with it. But, same quick search told me that it was also a more top-tier oriented bike. I can't see you regretting wanting brifters on it, or it being a waste for that bike. You've already put some money into it, and upgraded to point of aside from the brifters, it is a relatively modern bike. Depending on where you get the Rival group, you could get it cheap, or expensive. Depending on your rear dropout spacing, you may not need to coldset the stays. A lot of people have told me that since I've got 126mm spacing on the Panasonic I'm building up that I don't need to cold set, that just a little more effort getting it in and out should be just fine and I, or the components won't notice. You'll need a new hub, though, if you're going to 10-speed, which means either rebuilding your wheel or getting a new one.
Now, when it comes to it lasting. Framesaver, cleaning it regularly, maintenance, and TLC, the bike should last as long as you want it to, unless, heaven forbid, you wreck it.
Have you tried Rival though? Some people like it (I do), other people don't. Before you drop the coin on it, make sure it's what you want. Although, a cheaper option, might be indexed bar-ends, even though I know it's not what you want. Just a suggestion.
-Gene-