#1
I currently own a Mesa Triple Rectifier. I really love the sound (with a boost in front), but I've also really been digging the ENGL Fireball demos I've been hearing.

The Mesa simply doesn't cut it for me without a boost in front, and I'm starting to pick up on the effect that has on the amp's natural tone.

I play metal, period. It's what I cover, and what I tend to play in the future. However, I don't like stale high output tones. I use a Duncan JB in the bridge of my guitar. I like a well rounded tone.

I'd love to hear what you have to say if you've played both these amps as I've come across a pretty damn good deal for a used Fireball.
#2
I used to have one. IMO it has way too much bottom end. It sounds really great for chugga chugga stuff but for lead work, its lacking. Its definitely a rhythm players amp.
Gear:

Jackson Mark Morton Dominion
Mesa Dual Rect 2 Channel
Marshall JCM900 1960 cab