Is 'Infinite Fire' what I thought it would be?
You said this:
Lots of cut-and-paste overtures: Testimony, Testimony 2, The Whirlwind.
Lots of reprises, whether they are in the album or an individual epic: Testimony, Testimony 2, ?, The Whirlwind, One (kind of), All of the Above, Stranger in Your Soul, Duel with the Devil, So Many Roads, Seeds of Gold.
And from the looks of it, it seems like 'Infinite Fire' is along the same lines.
The beginning and end have the same feel and melody guitar line from what I recall. I'd have to listen again more intently, but nothing like what you said.
This album is very song-oriented. No real theme that pops out at you. If there is a theme or concept here, it isn't readily discernible. Do consider, you have other people besides NM and MP, and those others shine just as well (the guitar, bass, and vocals mesh VERY well with NM and MP, as does the apparent songwriting).
Edit: Infinite Fire approaches 12 minutes in length. To have a same intro and outro (basically) is pretty common in songwriting in most genres, and especially for a longer song, that isn't bad.