X-keys are smooth and have just about the right amount of travel. If you really want to build your own, you can do so with your own key switches. I highly suggest the X-keys. N52s, in my opinion feel cheap and cheaply made. (Considering you can get one for $25, they are).

The thumb button felt sticky and non responsive..... I don't like them.

X-keys sticks work great for out of combat stuff but "click" too much and are not great to pound on like the desktop or pros are.

The X-keys PS/2s are less programmable than the N52s - the USB version of the Xkeys much more so.

But that said, the PS/2 X-keys can still be programmed to repeat the key when held down, hold down two keys at once and toggle layers just like the N52. It just can't do amazingly complicated scripting like the N52 can do (like multiple keys held down at once, etc - things I have never needed).