I have a 2008 KLR, 2003 TW, and a 2005 BMW 1200S. Respectively the horse power is (+/- a bit for each bike) the TW is 16 HP, KLR 37-40 HP, and the K1200S has 168-170 insane HP. Ninja 250's put out about 30 HP and newer 300 Ninjas around 40 HP. Whoopty doo! Neither are powerful barn burners. I don't care who is riding it.
All three I currently own and have for awhile are great bikes but entirely different animals. KLR's will hang easily with Ninja 250's and 300's all day long. Last summer I waxed some guys ass on one while I was on my KLR. He saw ugly dirt bike as we sat at the red light and I saw sport bike wanna be. The KLR is a 650 so the extra cc's (as in 400 to 350 cc's) make a difference. I also hang with bigger bikes on the KLR within reason of course. TW >> Not happening. I ride the TW when I want to cruise slower and / or want to ride alone mainly but I will ride the other two alone also.
KLR's are too damn big for any real trail riding period unless you plan on spending half your time picking the heavy mule up. Saying is: They are good at many things and great at none. They are good for bigger trails and some dual sport adventure riding for sure but forget them on single tracks or tight woods riding, or anything very technical, rough, or difficult, etc; Also forget them for non-stop high speed freeway commuters. Now they are comfy at anything below 70 MPH and even 75 MPH on expressways but I wouldn't even do that every day regularly. It would get old fast. They will also cruise the hardballs at 85 but again, have fun with that and let me know how that works out for you. No sugar coating here.
Any higher powered sports bike will leave the KLR in the dust but in realistic twisty back roads riding the KLR can and will hang. A 250 or 300 Ninja will not walk all over a KLR by any means. Probably slightly quicker but not much. The newer 300 Ninjas even will not walk away from a KLR. I think the KLR's top speed maxed out is 100 MPH or a little above. The 250 Ninja's is about the same MPH top speed give or take an MPH or two. They might look fast but they are slow ass slugs lacking power JUST LIKE the TW's and KLR's. Get into the 600's and then you are into some fast bikes. Ninja 250's and the like are nothing more than peppy mopeds with Tupper Ware suits attached. Very similar to total horse power and top speed of a KLR but keep in mind the single is a 650 cc.
I ride my KLR a lot when I don't feel like dealing with the K1200S' raw power all day. It can be a serious work out. I ride with guys that ride FZ1's, Ducati, and many other big powerful bikes and keep up with them on twisty roads. The bigger bikes can and will absolutely leave a KLR throttling out of a corner but they also have to slow down for the next curve. You can keep up with the pace but on the KLR you have to work it. The KLRs will do freeways but it is not the best bike to do them on. In my opinion freeways and such isn't riding anyway. A KLR busting down the hardball at 85 MPH for many miles is not a picnic. Yes they will do it, but they really don't like it much. The TW's and anything 55-60 MPH and up is ill advised. Just not what they are for. Taking a TW on a freeway or expressway is a suicide mission. Highly not recommended.
So really it boils down to what type of riding you want to do mostly. How tall are you by the way? KLR's have very high seat heights. That isn't much fun either for me since I am 5' - 8". I manage pretty easily, but they are not the best height wise for riders that are not seasoned well if you are short. As someone mentioned above IF I could only have one bike and it was a choice between a TW and a KLR ((very tough choice)) personally I would likely pick the KLR and ONLY because it is more road capable, 450 more cc's, and it also is a lot of fun to ride. My KLR is probably my all time most favorite all around bike I've owned and I've had many, many bikes of all makes, shapes, and sizes. Myself I will never part with either my TW nor KLR. IMHO they are two bikes every rider should own. I'd sell my BMW before either of them but it isn't going anywhere either.
KLR's are fun bikes for many reasons but can not be fairly compared to a TW. Another cult bike just as the TW is but for different reasons. If your buddies don't ride like 18 year olds you can ride with them on your TW too. Expressways = Nope! Back roads rolling all day at 45-55 MPH occasionally gassing up to 60 plus, hell yes. Never mind on the 60 MPH plus part.... Granted your buddies will be quicker but you could ride along well enough on secondary roads, back roads, and roll thru some twisty's. If they want to run 60 MPH all day forget it on the TW. Just shooting it straight.
Tough choice, being the $500 bucks and TW trade in for a new bike. Can you clarify the deal? What year and how many miles is your TW and same for the KLR? Seems weird or a very good deal. Is the KLR used or new? KLR's usually sell for $6,400 to $7 grand now new and the TW's are $4,400 to say $4,800 if I am thinking correctly. Used on both bikes can be all over the board but both the TW's and KLR's seem to hold a decent value if they are worth having. Usually it is hard to find either bike under $2,000 used (always exceptions) that runs and you can actually ride. Even older ones seem to get a decent price if they are in working order.
If I am reading correctly with what you are saying I wouldn't think twice about trading a used TW for a new?? KLR. You are talking about a bike worth $2,000 more on new purchase prices. So a used TW and $500 bucks is a great deal for a new KLR. Just say'in! You could always shop for another used TW but you will miss that lil' goat.