i would get the tubus logo for two reasons:

1) lower rails - not too big a deal, but it makes it easier to have a loaded top platform, and still access top load panniers....
2) No bend at the front of the rack... so you can load stuff under your saddle, which is a good place to carry weight.

I use a tubus duo on the front, and it rules.

As far as front panniers go: You don't NEED them for packable volume, but most bikes handle 100% better with a weighted front end.... My GF and I just got back from a dirt road tour over a mountain pass here in AZ, about 150 miles in three days ( avg temp 75 and sunny ) and I use four bags, front and rear. SHe uses only rear panniers and had a harder time on the climbs, where her front end would lift, preventing her from being able to stand and climb easily. On the descents her bike was a lot less stable than mine, i could ride one or no handed while she had to really hold her bike in line. On pavement its not as critical, but i would rather have four half full bags, than two stuffed back bags... I ride my loaded bike no handed all the time on pavement- which is only possible (in my case) with a loaded front end and the slower steering that comes along with that.

I also had the room to carry home a horse skull and a cow skull that we found up in a wash in the mountains... so it might be nice to have a little extra capacity