The 690 is not a smooth motor, it is not far off the vibration level of the 640... Having ridden both back to back, there was not much difference between the 2.. That being said, the 690s larger power output is very apparent..

It is funny how there are the 2 different views on travel bikes, some guys feel they need 100+ horsepower and others are happy with 20... I prefer to go more to a midsize lighter bike and at the moment am waiting for someone to put out a 400cc bike so I can replace my aging 640..

I agree. I actually like both approaches, strangely enough!

My relationship with my 100+ hp bike is definitely not a practical one, and has very little to do with practicality of travel (perhaps it's marginally better for very long distances in a day in good conditions) but I just have so much fun with it and find it exciting to ride.

But make no mistake, that's certainly not a practical/functional benefit — if anything it's impractical and makes travelling more difficult, particularly in difficult terrain. For me, personally, part of the challenge is being able to build the level of skill to ride a big bike where others can only ride small ones.

Again, none of this is rational, it's emotional and probably quite heavily correlated with testosterone.

On the other side of the coin I totally see the benefit of lighter weight bikes with simpler mechanics that are not so performance oriented being practically speaking a great choice as a travel tool. If I was perhaps older, wiser, smarter I'd just buy a DRZ.

No question, 690 = power. I do disagree regards vibes. The 690 at least is less vibey within certain RPM ranges and latest version of this motor is said to be quite a bit smoother than earlier iterations. (2017)

The 640 vibes, in my experience, were BRUTAL. This view has been expressed widely by owners (mostly now X owners!), press reviews and so on. City Bike, San Francisco had several KTM 640 test bikes during my tenure there. I tested the '99 640 Dual Sport, '00 640 Adventure, '01 Duke 2 and 640 SM. We would get these bikes for 1 to 2 months each, so plenty of riding time by myself and staff.

I tested the Adv 640 in Nevada's Black Rock Desert. Bike was quite good in deep sand and rough rocks. Horrible on longer paved sections. (we were 80% off road on that ride) But, to contrast, I liked the Duke ll do much ... I bought one for myself! It had vibes, yes, but NOTHING like the 640 Dual Sport or ADV 640. By contrast, I felt the 690 was not smooth ... but smoother than 640.

True! But how can we ignore a bike like the KTM 500EXC? Granted, not the perfect travel bike in stock form, but seems to me that an ADV version could be created.

IMO, it's hard to beat your 640 in terms of HANDLING and LIGHT WEIGHT ...
and it's paid for! It's a great bike to ride off road, feels lighter than some 400's (XR400, DRZ400). Only thing missing is BULLET PROOF reliability. IIRC, it's lighter than the 690, power is not extraordinary, but adequate. You know the bike well and keep up with it's maintenance which means it could be RTW ready.

I'm going down the HP scale ... 250's. The WR250 is on my radar, will most likely become stable mate to my 62K mi. DR650. The DR will get a top end rebuild, the WR will become the new work horse.
My new (to me)'13 Ducati Hyperstrada is now my "street only" ride.

This summary post on ADVRider from a West African trip might also be helpful: Wanted RTW on a KTM 1190 - Adventuring Into The Heart of Africa.

1190 is ostensibly the same bike as the 1090. If you take a 1090, get a centre stand for it.