#2
The Fireball has shared eq for both channels, so that's a downside.

The mesa has three channels, separate EQ for each; but horrible clean channel.
Personally I would take the Dual. With a nice chorus, the clean channel is very usable. Just don't expect Fender-y cleans.
#3
Either way, you gotta try them both out extensively. Dont just take our word for it, ya know.

Id say Dual. Just cause Ive got a Triple and know it inside and out. I havnt had much time on the Fireball.
#4
Check out some audio clips, if you can't try them out. Something like this is truely subjective
1981 Marshall JCM800 2203
Mesa Boogie Tripple Rectifier 2 Channel
Avatar G412 4x12 Vintage 30s
Sobbat Drive Breaker 1
#5
I like darker tones so..... yeah you know....... Recto
Tone is all ...... well probably 75%, in your fingers.
The rest depends on your wallet's thickness !!

Keep the faith, baby!!