I've been trying to find a good comparison of the 560ti with 448 cores and the 560ti TOP by Asus. There is a 20 euro price difference, with the TOP being a little cheaper, but does that mean that the 448 has better performance, or is it just more rare and demands a higher premium. Also could the 448 be overclocked to match the clock speeds of the TOP?
The 448 core version is similar in design to a GTX 570 (480 cores), so it is a step up the ladder architecturally over the 560 Ti (384 cores). The main advantage of the 560 Ti TOP card is it's high factory overclock, which probably brings it into the performance range of the 448 core card at stock speeds. But then, the 448 core cards can overclock quite a bit and really do give top performance when overclocked, similar to a GTX 570 or even a GTX 580.
The 448 core models are worth the extra price, since they are very close in performance and design to a much more expensive GTX 570. The only drawback is that they are supposedly limited editions and will likely be rare several months down the road if you are looking to add another for SLI. They seem to be in good supply these days, however, still a couple months after their initial release.