>What are you using as a client application? I believe Entity Framework handles row level concurrency automatically. You need to have rowversion field in the table.
>
>I can also recommend reading very long but excellent article by Alex Kuznetsov (he wrote a book on this topic, but I didn't read it, called 'Defensive Programmging')
>Developing Modifications that Survive Concurrency

Our primary consideration was performance. Entity and Fast are not good friends :)
We use Dapper (considered a micro-ORM) which isn't really the same thing as Entity but it's fast as hell and simple to use.

http://code.google.com/p/dapper-dot-net/

http://samsaffron.com/archive/2011/03/30/How+I+learned+to+stop+worrying+and+write+my+own+ORM

Performance of SELECT mapping over 500 iterations - POCO serialization
Method	                            Duration
Hand coded (using a SqlDataReader)      47ms
Dapper ExecuteMapperQuery<Post>         49ms
ServiceStack.OrmLite (QueryById)        50ms
PetaPoco	                        52ms
BLToolkit	                        80ms
SubSonic CodingHorror	               107ms
NHibernate SQL	                       104ms
Linq 2 SQL ExecuteQuery	               181ms
Entity framework ExecuteStoreQuery     631ms

Thanks for the link.