Me and my wife have an XT660R each. We are lovin' them. Lighter than then the 660 'tenere, cheaper to buy, better MPG, and lots more comfortable too. Downsides are a smallish tank for travel - about 180miles and you are close to fumes only, a bit less protection from the smaller screen (although personally I prefer this), and fewer off the shelf farkles.

Mods to make: see you how you get on with the throttle, they have a reputation for being snatchy - XT660.com do a thing called the Kev Mod which fools the ECU into running richer.

Change the exhausts for lighter silencers or an even lighter 1:1 system (Metal Mule, OffTheRoad.de and a couple of other places do them. MM seems to be the cheapest. I got my MM system 2nd hand; wife has Akrapovic 1:2 silencers

A decent bash plate if you need to go off road. Note the various 1:1 exhaust systems give 5-6cm extra ground clearance as they re-route the headers. You will also need a bash plate designed for the rerouted exhaust though. Again MM seem to be the best (I have one) and my wife has a Touratech bash plate, which is huge.

Handlebars have a reputation for being easily bent although my wife has dropped her bike several times with no damage yet. But some sort of Renthal seems to be favourite - check on 660.com

Acerbis or Barkbuster handguards always a good addition.

Luggage:Not the best bike for attaching luggage to in standard trim, although lots better than many other dual sport bikes. We use Giant Loop great basin bags and a GL tank bag. We decided we didnt want to add all the extra weight of panniers, pannier frames and topboxes. I am busy farkling to get a couple of Kriega tail packs to act as tank panniers and also looking to fit a couple of tool tubes. Finally we have a B&B luggage rack picked up on a visit to Australia. Well made and worth looking out for. I am thinking about attaching a Rotopax fuel cell to either the luggage rack or to a bracket where the left hand silencer used to be.

That's all I can think of for now, oh, except the headlight is unfeasibly good for the size and look of the unit.

Enjoy your bike I think they are a cracking bike. We will be in Pembroke in mid-Feb on it with a group from XRV.org.uk. If that's your part of West Wales we would be more than happy to meet and chat.