the yzf600 is like the lower grade version of r6. Its like in the same class as the katana compared to the gsxr. They are still respectable, but I see them more as sports touring bikes then real super sport bikes. Personally, if you look around, not at dealerships, but at private party, you cold find a great deal on a modern 600cc bike. 3700 could get a decent 2000ish r6, cbr600, or a gsxr.
Carbs aren't that bad, just old technology. Carbs on modern bikes are fairly good and won't cause too much trouble. You generally have to clean and sync them some every 10k miles or so, depending on what bike you get. The YZF also has less of a killer powerband, good for a starter bike, but still powerful for most new bikers. The sv650 is a totally different bike. It houses a v-twin engine and the torque band is much different then an Inline 4. If you already had a starter bike and looking for something to upgrade to, this is not much more than a can of tuna for yah.
You maybe able to find a cbr600 f4i around 4 grand, maybe less. check your local classifieds.