done a few trips here and there and the smallest bike I've ridden for any distance is a 250, my own TTR250 and in Thailand a 250 mini dominator. Gotta say the Thai riding was probably 60/40 road and off road but the off road was high becasue I was so happy and confident to take the bike away from the tarmac which meant I got to explore away from the road and see more. On the winding corners it was great fun and more than powerful enough given the rest of the traffic.
The TTR took me to Morocoo and yes the long ride across the windy plains of Spain were a chore but when I then spent months exploring Southern spain including lots of beach and mountains my 250 was an absolute joy, in soft sand you had to power on but once it was up and going it was great fun. 2 up when someone needed a lift i just took it easy and enjoyed the views. My TTR had the big 23 litre tank which meant I didnt need to stop very often.
I prefer the thinner flatter seats, i have short legs so the better stand over height and lower weight are a real plus for me, never found that my sheepskin over a think piece of camping mat were not up to a good 12 hour plus of riding, lets be fair you feel a 12 hour ride on any bike!
Would more power have helped absolutely but I don't think I would want lots more weight, My 660 tenere had the extra power but I always found the extra weight and wide seat/tank hampered my enjoyment away from the tarmac and it wasnt much fun to pick up, having a bigger tank and fairing meant it suffered badly in cross winds too.
I have a sv650 on the road its got a lovely engine but you really notice the weight when moving the bike around, it drinks fuel and back tyres wear out fast and cost a lot to swap!
What next, ideally a do it all bike that looks good and is not too heavy, got my eye on the new Fantic Cabelero 500 but need to wait until they come down in price on the used market andsee if they prove relaible or maybe a scrambler 800.
An easy pick would be the Honda 250 Rally, I love the looks and I'm not expecting it to set the world on fire

or a ktm 390 adventure but KTM seem a bit slow on the uptake