Is it really night and day

I just read that someone went from a ARC ref-5se to a Ref-6. They claim it is a night and day difference. For some reason I find that hard to believe. I can see there being a difference but night and day to me is an exaggeration. I'll tell you why I think this way. I had an ARC LS-25 for about 10 years and I always thought It was a good pre-amp. One day I got a bug up my ass and decided to upgrade to a LS-27. 

While I will agree the 27 is better than the 25 I would not say there is a night and day difference. Now that is a spread of about 10 years in a model. So of course you do expect some improvements and I have received those. 

Now going back to the Ref-5se. I think it has been around about 3 years. Now they have the Ref-6. So in 3 years there is a night and day difference between the 5Se and the 6 but after a 10 year period between the Ls-25 and the 27 there are a few minor differences.