Shawn Hargreaves just posted this: http://blogs.msdn.com/shawnhar/archive/2010/03/12/reach-vs-hidef.aspx
I suggest you have a read through it if you are interested in the kinds of things I post on this blog, especially the Light Pre Pass technique.
One of the key parts of Shawn’s article are the changes that will be made to Render Targets, and the bucketing of the RenderTarget/Texture formats into the Reach and HiDef profiles.
It would be safe to say that future articles here will require the HiDef feature set. I make use of some of the Render Targets that do not exist in Reach, and while there may be a way to use a Reach Render Target, for the purposes of conveying the technique, I will not be adding extra code to support it. I may however note where alternatives can be used, and hint or mention how to use them.
I know I have previously used BGRA formats in my sample, and in future this will become RGBA, no big deal. I won’t change the 3.1 sample for now, but if I need to change other things to upgrade it to 4.0, then that will be “fixed”.
This shouldn’t be much of a problem, if you are going to be using the articles I plan to write, then you’ll have a computer that works with HiDef, or an XBOX.
As a side note, I no longer have a valid Creators Club subscription, so I have not tested the recent Light Pre-Pass article on the XBOX. If anyone has any issues let me know and I will try and look into it. I plan to get a premium subscription soon and test future articles on the XBOX.