You have almost answered your own question. UpST8 is right I have never been happier. I think it is the best bike I have ever had.
I spent a couple grand trying to make the 800R comfortable for ME and just couldn't do it. I put on a windshield, raised the bars, tried a couple different seats, none of them worth a damn. There were other things I bolted on but cant really remember everything. I just could not get comfortable.
The 700GS was a good fit for ME right off the showroom floor, all I added for comfort was a windshield to get the wind off my chest. I got it from Cee Bailey's for $120 and it screwed on in 5 minutes, there are even more choices now that some time has gone by. It is about the same height as the one on the 800GS.
I think it is a lot more comfortable, the pegs are set forward more, bars are a little higher, and you sit upright. On the 800R I was seated more towards a sport bike position, got hard on the wrists and knees pretty quick for an old guy like me. I have spent all day on it quite a few times with no issues, I could never do that on the 800R. Mine came with the comfort seat already on it, and it actually is comfortable.
I feel it has plenty of giddy-up for what it is and I have no problem overtaking traffic on the freeway, been up around a 100 MPH a time or two with no problem. I noticed hardly any difference in power between the 700GS, 800R and an 800GS I rode briefly last week. I went easy on the 800GS, it just had brand new tires installed and wasnt mine. We all ride different though and I don't ride like its a race every time I get on the bike. I feel it is geared well for both dirt and the street, I am however a complete off road novice. A more experienced dirt rider may have a different opinion.
There are far more accessories available for the 700 than the 800 because of its close relationship with the 650GS and 800GS. There is aftermarket luggage available for both but if you are going to stay with stock luggage and work it into the financing like I did, you will be happier with your choices for the 700. Stock luggage for the 800R is ugly as hell.
Mine is a daily rider and hopefully will be my commuter real soon. It gets 50-55 MPG depending on how its loaded and how much wrist I use. For your wants and needs I think its just about perfect. The GS decals do not mean you are required to take it off road, but you can.
I love mine and while the 800R is a fine bike it wasnt right for me and I regret buying it.