RiddleOfSteel

Are you coming from a Schwalbe Marathon level of durability or something a few galaxies closer to the Vittorias? You have to look at your expectations, your riding environment, your riding/bike style, your general awareness of hazards, and your present flat rate with whatever normal tires you run, and then assess. I don't know any of those (for you) apart from the Vittorias being described as a clincher version of a literal race tire. If you're hoping they'll be a Gatorskin, you're gonna have to mentally adjust (both good and bad). Are they tracing paper thin? No. Are they pretty svelte? Uh huh. Will they be more flat-prone than a Super Ultra Distance Tourer Anti-Flat 9,000 EXTRA-THICC Devil's Pass 700x38? Of course. Will they feel good? Very very likely.

I've been able to snag all but one Vittoria pair (of the number have) for super cheap. They were used. They have small nicks and cuts and less tread. The ones on my Davidson are a little bigger. I have standard tubes. I am a pretty aware rider--not a klutz, not oblivious to potholes and various road imperfections. Not hopping curbs, nothing stupid. Seattle streets have plenty of rubble and junk. Plenty of opportunities to murder tires. I have had very few flats with them. I carry a flat repair kit (or not) and just ride. The tire is just so nice to roll on, and they're properly light.

What wheels and what bike are they going on?

[Edit: Pardon the extra sauciness of my response here. I think Vittoria's are good tires and this should live up to that expectation. But there's always risk with performance. We see the best performance out of an F1 car, but at the expense of durability and any sort of practicality. So you need to know where you presently stand regarding durability vs. performance, and decide how far you want to travel from your 'ideal'. The world can talk about tires until their blue in the face, and I can and have read tire reviews for hours. After a while, the only way you're going to get an answer for yourself (or me for myself) is to buy and ride them.]

Piff 

They'd be going on a 1982 Miyata 1200, and Wolber Alpine Super Champion rims. Currently I've got some Continental Grand Prix Classics, but I'm just getting ready for my next pair of tires. As for my riding style and road characteristics, I'm pretty good at avoiding debris and treating my tires well, but I do have a few routes that require a little bit (couple miles at most) of riding on well groomed dirt trails.

I feel like they'd be alright for the kind of riding I do with the Miyata. I've done alright with the Conti tires for the most part, but I know they're no race tire.

RiddleOfSteel

Yeah, that can be a tough call. I have no problem with 'princess tires' (my term) being pavement only. Helps when one lives in a city, but still, zero gravel or dirt for my Vittorias. The SLs would be a very special tire for a very special ride/ride type, and I think that's fine. Not every tire has to be accommodating of all surface types--it's why there are categories of tires. I like the specialization because it isn't a compromise.

I continue to be surprised at what my Vittorias do shrug off as we all can't be perfectly aware every second when we ride. Part of me thinks that the dirt trails--especially hard-packed--would be fine, but you know the makeup of them and the non-dirt stuff that's in them, so that'll be yours to mull over.

Piff 

If I'm being honest with myself, the responsible option are the Michelin Pro4 Endurance tires (also on my craigslist) given how I like to explore on my bikes...I think I'll pick up both for fun, the SL is only $30/tire and the Michelin only $25 each (but I bet I could get the Michelins for less).

bargo68 

Lowering my saddle. I figured out all my saddles were about 1/2" too high!