I have ET-65 top and Vet30 bottom in 1960a. The Cab I found and bid/won for $150 local pickup. New grill cloth and tolex (Green in color).
If you are looking for a quality used Cab at a bargain, you can find on Ebay or Reverb at a local pickup. Sellers are glad to unload local pickups, even at a steal. Steal is the operative word. Don't feel guilty about low balling. If it's listed, they are looking to unload. Sell your MIC Cab and go for the gold!
Anyway ET-65/Vet30 combination features the Vet30 with a little bit of a bark and the ET-65 tries to tone it down. It's a complimentary combination. It works well with ANY Amp, IMO. Very, very useful in that aspect, whereas my boutique Amps tend to be picky. It doesn't really sound like a mixed Cab. Just one FAT wholesome sound.
X pattern was way too topsy/turvey for me.