I try to explain what I mean... See how in this song here the intro melody and the solo at 1:56 - 2:14 gel pretty well, they're not the same notes but they just feel together. I think that's one of the things that made especially the blue and green COB albums good. What is it that makes this solo feel together with the intro or whatever, is it because the background riff and drum pattern is the same? I think it's both the melody and the background.
From RRF I remember NMF guitar solo is quite wacky, SKO guitar solo has a catchy background riff, RtHaB keyboard solo is experimental, Ugly guitar solo is a downgrade of FTR solo... that's all I remember, cos they're not written in this epic way.
I think the solos need epic melodies, but they're also perfect opportunities to cast in some gorgeous riffing like Tie My Rope (3:07...). I really love it when this shit is done the way it should. This TMR solo section doesn't even have that epic melody, it's just a genious riff and beautifully done technical shredding, but even so it's amazing for this type of song. Then when you have a balladic song there's a different background and when you have an aggressive song there's a faster background riff.
Sure the solos in RRF are very technical and some of the riffs quite complex, maybe it's small differences but I personally love it when it's more catchy. Maybe the band's perception of music changes as they get more experienced in the technical side, but I think it should sound interesting and you should be able to memorize the solos so you rhyme and whistle them. I just listened to the solos of RRF and PMS and realized there's no way I'm going to remember let alone whistle this shit. It's what I think makes an epic song, that it's not just technical notes gunfire, but actually something very characteristic that won't stop playing in your head.
I recognize the pros of RRF these days as it's grown distance from the previous album, just personally I'd like the next album to steer away from thrash and go for atmospheric doom metal and industrial influences together with the best elements of old COB. I think this band still has a stone left unturned in industrial metal influences.