The stock speaker seemed pretty brittle and somewhat shrill at the top end. I am very happy with the ET65. It warmed the amp up but most importantly I have many more tonal variations. I can now use the gain channel by itself with great results or I use the clean channel with a Strymon Sunset. The Sunset works extremely well with the ET65. It is 9 pedals in one. HIGHLY recommended! Guitars I tried were a Fender Duosonic HS, 1970 Univox (LP copy), Parker Fly Deluxe, Godin LG with DiMarzio virtual P90s and a stock American Stratocaster. They all sounded great! I am really happy with this speaker!
Awesome ... and yeah, you've hit upon the real magic of the ET65 in your comment I have many more tonal variations" ... that's the ET65!