wackyvorlon wrote:Is it a worthwhile purchase, or a waste of money?
You're going to get people landing on both sides of this question... but, for me, a cut-away lock was a useful tool when first learning. It helps you to make sure that you're hitting the pins that you think you're hitting, and it's also helpful in showing you what's going wrong when you're first learning how to rake, etc.. Having said that, though, cut-away locks can also be a really quick way to pick up bad habits when picking. (Every lock you work on will have different characteristics -- high/low pins, binding order, feedback, etc. -- and focusing too much on one lock will only get you so far in developing your skills... but it can be helpful when you're first starting out.)
If you do buy one, in order to get the most out of working with a cut-away I'd recommend trying to quickly get to a point where: (1) you're not looking at the pins while you're picking (i.e., stop picking and then peek at the cut-away portion to see what's gone right/wrong); and, (2) you also pick up some cheap non-cut-away locks that you also frequently practice on.
In my experience, the cut-away locks targeted at beginners tend to be designed to be
very easy to pick (even if you couldn't see the pins). They're good to quickly build up confidence... but they're not going to give you what you need in order to move onto more advanced picking, so you'll have to judge your budget accordingly.

Hope that helps...