Hi Gareth,
I've been using the exposed cores models in stainless steel and nickel.
The stainless steel were very similar to the LaBella Super Steps, just a bit softer to the touch and without the extra overtones you sometimes get with the badly made exposed cores strings (too long exposed core is what is generating these overtones or extra out of tune harmonics). It's something that is happening very often with the Super Steps and even the Fodera Anthony Jackson strings !?!
But the nickel exposed cores were, to me, even better on all aspects. Smoother and better sounding, more even and consistent.
Both types lasted longer too with that piano like tone typical of these strings.
That said, even if I live in continental Europe, they are not cheap at all. They are top notch quality and there is a price to pay for this.