What are the advantages to a Class A amp & what are the trade offs?


I've never had a class a amp but am considering one now. So what am I getting myself into?
128x128artemus_5
Excuse me, but what is an F5 amp?  I can't find it in this thread.          I found excessive global negative feedback is also not my preference.  I like the VAC Class A/B amps with 6 db of same.  
Post removed 
Wasn't the XA25 the amp with superlative technical reviews?  Thanks for the info.
Post removed 
Post removed