When will the c# (and LINQPad) samples for LINQ to Amazon be updated to support the new mandatory signed request syntax?

I would love to have complete database independence and do away with all my stored procedures (I already have no business logic in the SPs) But my DBAs say performance will suffer (we run sql server 2005) Is this true, is this a myth?
Thanks - your response was very helpful! - I will do the profiler tests. We do have 1,000,000+ row tables, so SPs might be a necessary "evil"