New DR or factory upgrade DR

I don’t think so as everything essential for that soundupgrade is being replaced. But perhaps more techie oriented people can give you more certainty.

I believe when you get an upgrade (and service) the device is brought up to current specification in the vast majority of cases.. so it’s the effectively the same performance as new

The DR upgrade does not include a recap. So while the upgraded unit is the same as a new one in that respect, please take into account the age of the unit and if nearing the recap age, you need to add the cost of the recap to the upgrade. That might help you make the decision. When I had my 250.2 DRed, the cost of the recap on top was significant but the unit was only 2 years old so I had the DR upgrade only.

ah ok good point.  And recaps are recommended at about 10 years, right?

Pretty much yes. But if you a long way from an authorised Naim service centre and units have to go to different countries or the other side of a large country, you might want to do this sooner to kill two birds with one stone. A 7 year old XPS won't need a recap. But if you are spending a fortune sending it off and paying customs charges each way and stuff, it may be worthwhile rather than do it all again in a few years.

I don't think that applies to your location but I mention this for the benefit of those like me who live far afield from places of service.

I upgraded my quite new 300, but traded in my Supercap. The Supercap would have needed a service and the trade in offer was generous enough for me to go for it. Obviously, the value of the replacement is higher, if I ever move it on. There was also the suggestion that Naim make subtle improvements over the years which are not announced, but do mean the DR upgraded units may not be quite as good. 

Keith