Quad 405 Updated .... Any Knowlege on this upgrade

I am trying to deciding if I should just buy a newer (used) ss amp or up grade my old quad 405.

Has anyone listened to a Quad 405 after updating?

According to the Quad builder .... I quote .....
I highly disagree with so many of these so called "Audiophiles" speak without ever having dealt with products. I own extremely high end audio equipment and a modified 405 is one of the best. As a matter of fact dual mono Quad 405's are the best I have ever heard."

So I am looking for some truth ..

BTW
I am currently using
Audio Research SP5 pre amp
Quad 405 dumping main amp
Pioneer Elite DV-48AV
Polk Monitor 10's
Velodyne VRP 1200 sub

Thanks in advance
Tony in Florida