The fetch quest and lots of running back and forth in the Witcher1 are not missed.
They're not missed because they're also present in TW2.
Speaking of the path(s) you mentioned:
On Roche route in chapter 3 you can influence the state of Temeria, where Roche ends up and (as on Iorveth path) sorcerers´ position in the world.
If you choose to help Roche:
If you give Anais to Temerians, Temeria retains sovereignty (at least if Henselt is dead) and Roche will serve Natalis, if you give Anais to Radovid, Temeria ends up as a protectorate of Redania and Roche changes uniform and will serve Radovid.
Dethmold is dead. Conclave and mages are fucked due to Shilard´s speech.
If you choose to go after Triss:
Temeria is divided between Kaedwen and Redania (at least if Henselt is alive). Roche ends up with Anais in some unknown location. Dethmold is alive.
Conclave and mages are ok since Triss´ speech tramples Nilfgaardians´ plans in this regard (Radovid merely attempts to arrest Síle instead of starting a full blown "witch-hunt").
There are some other nuances along the way.
Altogether that´s good enough for me, though I wonder how many of these changes will have influence in a potential sequel or an expansion.
Yes, I know all this. I played Chapter 3 a total of three times to see all the consequences. I was just a little disappointed that none of it makes any tangible difference in the epilogue or ending. The political outcomes do nothing to affect Geralt or the gameplay in any way. It will be interesting to see what effects, if any, that have in The Witcher 3. Assuming we import our saves again.