I think the slidelock looks good but it does seem a bit pricey. Another option might be to get a ruler grip like this one
http://www.missouriquiltco.com/shop/...r-sku-tgq002-c
and just attach it to a long ruler then you have the handle and the ruler too.
I find the more and more I use my ruler to measure rather than my cutting board so I don't think the slidelock would work for me.