F and E are almost identical except for fairing. I would keep looking if you're planning on keeping the KLR. GS500 is somewhat faster and slightly more room, but not much. It's only a minor increase in both departments. Unless you and your wife are jockey sized it won't be enough of a difference to be a game changer.
I'm a Suzuki guy, but suspension/brakes/fit/finish are all bargain basement. If it were me I would hands down pick a SV650 over the GS500. They are available in the same price range if that's a factor, and have 50% more power than the GS (double the KLR) with better suspension, liquid cooling, much better brakes, etc. Upgrades and farkles are readily available and better priced due to larger market. Also a GSXR front end is a very simple swap onto a SV which transforms it into a weapon on curvy roads.
For a little more money you could also get a DL650 (Weestrom). Same bulletproof motor as SV with slightly more upright/touring ergos than the SV. Again Strom is much improved fit/finish over GS.
The GS500 was built to hit a low entry price point and it shows when compared to most anything else. Don't get me wrong it's a good bike (the unfaired version is a GREAT learner bike), bulletproof motor, etc but like the KLR it's all 1980s tech. Due to low MSRP it's a good value comparing new to new, but doesn't hold its own on the used market because so many other bikes in that price range are better outfitted from the factory.
Last edited by Whitebread117; 12-29-2011 at 05:15 PM.