controlRenderingCompatibilityVersion move to 4.0?

Anyone experiemented with changing controlRenderingCompatibilityVersion to version 4, and try using some of the better clientIDMode options? I have some code Ive added to my site which has the long long autoid's appended to them, so it looks like ctrol001_ctrl001_something_controlname.property="value";
(repeat this 50 times and you get the idea)

I'm considering switching this over but not sure if it will blow up or not.

further info here http://weblogs.asp.net/scottgu/archive/2010/03/30/cleaner-html-markup-with-asp-net-4-web-forms-client-ids-vs-2010-and-net-4-0-series.aspx

I have played with this feature on a few projects.  I am sure MS has tested this thoroughly, but the way web forms renders a page, I have a hard time using the clientidmode on anything but the simpliest of page layouts.  Of course once you get that simple, then why bother using serving controls at all. hmmmm.

To me, I think if you are using web forms you just do things the web forms way.  Otherwise MVC.  I am really starting to like MVC.  My 2 cents.

i love mvc too, but doesnt really help with this ;)

i tuned on the feature and set an option that lets asp automatically trim some unecessary id info off, it seemed to help some. I'll roll with this for now.

I guess my only beef is that it just seems to good to be true.  There is a bit of a 'black-magic' feel to web forms that I still haven't completely come to accept.