I have it running on 3 of my 594 boxes. Version 4.5.1 has been very stable for me on all platforms.
Version 5.0.1 bit me on my custom MAPI policies. The CLI is totally rewritten in 5.0.1 and your MAPI traffic that use to be at the bottom is now the top of the list. We had tons of odd issues from Linux users with Thunderbird not being able to pull mail to random disconnects for clearcase traffic. I had to downgrade from 5.0.1 back to 4.5.1. TAC eventually told me I would have to upgrade again and reorder my policies putting MAPI traffic back at the bottom if I wanted to move forward with newer code.
Also 5.0.1 looks nice, but there are some losses in functionality. You can no longer sort the top WAAS boxes by volume of data by WAE unit, you can only sort applications by traffic volume. Looking at TCP Connection Trend report no longer shows you all apps consuming your TCP connections. You can view all connections consumed or select upto 3 applications by name. Also once a policy has been created you lose the option to Enable/Disable Statistics for tracking that application under Device Traffic Summary. You have to delete and add the application back to turn on tracking of statistics. 5.X needs some polishing up for sure.
There are other issues with visibility into WAAS performance with 5.0.1. With all that being said if you have not written any custom policies and if you do not use WAAS to track health of a branch location and see what the WAN is doing then you are fine going to 5.0.1 or 5.0.3. I still run my CM on 5.0.1 to force myself to get use to the new layout. All my WAAS boxes are on 4.5.1 and are rock solid.
