I'm another fan of the Scor-It. I don't have a Scor-Pal but I do have another make of board that uses that same construction (molded grooves at set intervals) so I'm comparing with that.
Because the Scor-It has the steel rule for the score, the line is much crisper. That's great for folding but even better if you're using the scored line as part of the decoration on a project.
This card in my gallery was done using the Scor-It and I love how crisp that grid came out. You do have to take a little care with your alignment to get even spacing since you're moving the paper each time but the freedom to score exactly where you want more than makes up for that for me.
I love the solid feel of the Scor-It and the non-slip surface of the rubber mat on each side of the central rule.
What this thread is really going to tell you though is that everyone is different! If you can get to play with the two tools before you buy, you'll be able to make a much better judgement about which camp you fall in to.
Have fun with whichever one you choose!