Expediting Express Requests - comment by carrie

Sarathy,
 
Although it is possible,  I would not expect tactical queries to be impacted much, if at all, from competition with express requests.    Express requests for the most part are extremely fast (that is why they are named express requests) unless they have to wait for an AMP worker task.  Most of them go to one AMP, not all-AMPs.     In addition, if your tactical applications are well-tuned, primarily single-AMP requests, then they will mostly use work08 anyway, not work09, and there will be no conflict at all.
 
The only way to know if there is an impact like you describe is to monitor the SAWT table for inuse counts and max inuse counts for work09, before and then after you change the EnableExpediteExp setting.  If max in use counts for work09 are higher than your reserve number in either case, increase your reserve number.  
 
Flow control on work09 is pretty unusual.  Even if a work09 message cannot get an AWT, that work09 message will be placed in the message queue ahead of work08, work00, work01 and other lower work types, and will get off the queue sooner than those others, so flow control is very unlikely. Most commonly it is only workone messages that experience flow control.
 
The benefit for expedite express requests for all requests is that it adds a small boost in parsing times for all queries, which is often desirable.  However, option 2, which only provides that benefit to already-expedited requests, is a fine choice as well.  It's up to you.   
 
Thanks, -Carrie