I've got an older 'Crossbow' and the newer 'Signature.' They both work fine on my top-loader (Pro-2M). I thought the Crossbow made a small but noticeable difference -- mostly noticed more weight and ease to the presentation -- enough to persuade me to try the Signature. The Sig is better still, pulling more micro-detail out of the pits and increasing ambiance, while still sounding smooth as silk. Night and day, no, but still significant.
Hard to ever tell anyone if a tweak is worth the extra money. You've just got to try it and see. I've sold off my super-expensive digital cables (Marigo and Sextet) because, though I thought they were better than the cheaper cable I'm using, I ultimately didn't think they were worth the extra $$, but I still use the Marigo mat.