Audio Research Reference 250 capacitor issue

I was looking at buying an used Ref 150. I got the serial number from the seller and asked ARC tech when it was manufactured. It was in 2011.

I then asked if there is any difference in terms of innards - components used - in the 2013/2014 Ref 150 versus one manufactured back in 2011. He told me the earlier ones has white Teflon caps, but due to 'no more supply' of those caps, ARC switched to the gold color Teflon caps.

I then asked him if there is any quality (sound quality) difference, and he said "you probably won't hear any difference".

There was no mention of any reliability aspect of that white cap versus the new gold cap.

this mix of white and gold cap got me thinking ...

You were offered the whole kit - which consists of all the caps, for what reason?

Because ARC feels its an 'upgrade' (i.e, better parts, better sound)?

Or because ARC doesn't have the old white cap in stock any longer, and because you cannot have a mix of them in your amp, therefore you had to buy the whole kit and replace all the caps? But then, one of you mentioned that your Ref 250 contains a mix of white and gold foil Teflon caps. So what's the deal then?

If you have one of the more recently manufactured amp with the gold foil Teflon cap, and one cap goes back, does it mean that you only need to buy/pay one cap as replacement?

I am going to call Kalvin at ARC and ask him these questions tomorrow.