Shorter cranks?

[TsPoet]

I'm 5'7" (on a tall day) with 33" inseam - I have 165s on one bike and 170s on the other two. I'm looking for 165s on ebay to replace the 170s, I find the shorter cranks much more comfortable.
Then again, the difference between 165s and 170s is very little (less than 0.2 inches). I honestly wonder about going even shorter. If you are interested, a guy named Mark Stonich shortens 175s to any length you like, he does an absolutely beautiful job, they look like manufactured cranks, not like they've been shortened. He has to use 175s to start with because 170s are hollow or something.
http://bikesmithdesign.com/