The Union Into the West is good. It almost reminds me of Revere. Does your friend know them? because I just noticed a friend of mine whose a huge supporter of Revere, also has this Her Name Is Calla album on his rateyourmusic.
In just looking at the track list to The Quiet Lamb, there's a couple lengthly pieces. A 17 minute song called "Condor and River" and then 6 more songs that are between 6 and 8 minutes. Length doesn't necessarily mean a thing, if the music flows, but I can't deny, some Post Rock ends up being so slow and methodical, at best it ends up being mood music.
I still need to check out Revere. I was recommended them a little while ago, but accidentally picked up "The Revere" instead. My friend doesn't know Revere, though, so they're probably not the same person.
As far as The Quiet Lamb, it is sometimes slow and minimal at times, but very rarely methodical. It's often very dynamic within one song, instead of the often mundane kind of post-rock song which only repeats the same simple motif and doesn't take it anywhere. The album also mixes other styles in with the post-rock, including classical, which is a big part of the sound, and folk. The vocals (which are very, very good and often recall Buckley) tend to help keep the music interesting.
Also, Condor and River is actually one of the best songs on the album, and the 17 minutes go by very quickly.
Long Grass is absolutely beautiful in the studio, too.