I fully agree with HansP that the Varadero is a road bike only. Don’t let the DP or DS ‘classification’ fool you. There’s nothing dual sport about bikes like the Varadero, V-Strom, GS, Tiger, Quota, CapoNord, Multistrada, etc. The manufacturers of these bikes only responded to the demand in the market for ‘adventure style’ touring bikes as obviously demonstrated by the success of the best-selling GS series, which started the trend. The word to pay attention to here is ‘style’, because the design brief for the engineers was dictated by the marketing departments. The marketing guys know all too well that 99.99% of buyers of these bikes will never venture off the tarmac, but nevertheless like the I-might-just-head-off-to-Africa-on-my-next-trip image these bikes portray. Basically, the marketing of these bikes is based on selling dreams, a bit of a variant on the ‘What wins on Sunday, sells on Monday’ theme. And selling the dream of riding-around-the-world or perhaps winning the Dakar has determined the styling of these bikes. It never ceases to amaze me that people think that these DP/DS/Dakar-look-alikes are even remotely capable of following in the tracks of a real Dakar rally bike. These bikes are heavy behemoths that were never intended by their designers to be ridden offroad, apart from the odd short detour onto a nicely graded gravel road in order to gather some dust or mud specks necessary to earn street cred for their latte-sipping owners.
(Did I just say that?)

Please don’t take offence, Gary, but the fact that you even wonder if a Varadero “has much rough dirt road/single track capabilities” not only had me laughing out loud, but convinced me that you have no experience riding ‘rough dirt and single track’. Because if you had, you would never even have contemplated the idea. But you’re not alone in adopting this mistaken belief in the (even limited) offroad capabilities of these big DP/DS bikes, as most RTW-trip candidates have a road-riding background and no idea what dirt bike/single track riding entails.

Returning to the bike in question, not only the bulk and weight and the linked brakes determine the Varadero’s real habitat, but also the cast wheels are a definite ‘no-no’ for offroad riding. This said, the Varadero makes an excellent long-distance touring bike. It’s extremely comfortable, very reliable (it's a Honda!) and low on maintenance, and is easy to handle (on the road). The engine is more than powerful enough and very smooth. It’s IMO one of the best all-round touring bikes on the market, more comfortable (because of better wind protection) than the V-Strom, albeit less powerful. And certainly a lot more fun to ride than any big GS.

I can't imagine anyone wanting to improve on the Varadero's saddle, as it's extremely comfortable, never heard anyone complaining about it. The capacity of the large standard tank is also more than adequate. Besides, if you see the bulk of the stock tank, who in his right mind would want to make it even bulkier? Yes, I know... the Touratech guys...
(Did I just say that... again?)

I have ridden a Varadero (the FI version) on trips in EU in various conditions, ranging from T.W.O.-blasts-down-the-German-Autobahn, to narrow slippery mountain roads (rain, ice, snow), to gravel and dirt roads in the German Eiffel and French Jura mountain ranges, and to even embarrassing sportsbike riders during a track day in northern France (grinding up the foot pegs to half their length, which admittedly is not hard to do on the softly-sprung Varadero). IMO, the Varadero is a fantastic bike in its class, and it would certainly be happy to do a RTW trip if you stick to riding the black stuff. But if your RTW trip involves dirt roads you better start looking elsewhere…