never got one from winchester but did get several from colt. i only see 2 benefits to a factory letter: if the gun in question is a high end $$ item and there is or even could be the slightest doubt as to its originality or if there were some significant historical provenance such as famous former owner. if it's just a run of the mill factory gun and has never been altered i seriously doubt you'd even recover the cost of the letter. don't know what their's are; the last colt i got was $60 but has been a while and i think has gone up. i believe winchester used to be a little cheaper.
roger
