^yeah.
If I were you I'd hold off on the pedal till you get the amp. You may not need one, or you may need a differently voiced one, etc.
I have no idea, lol.
That being said, a boost pedal won't hurt an engl, lol. And if you go for the thunder, you might need one (no idea, I haven't tried it). And it wouldn't hurt for the screamer either- the high gain channel sounds kind of metal, you'd get, I'd have thought, a better lead tone by boosting one of the lower gain channels (crunch for example), since it's much more middy and less trebly.
That's what I love about my savage se- with the rough button engaged, it's metal, and then when i switch it to smooth, it's high gain, but for solos.
Unfortunately, the savage and savage se is the only engl with this feature- although the se will do the savage/savage se tones too, since it's uber-versatile.