I had a testride of the NC700X when they first came out. In many ways it's better than the Wee, but like you say it's definately lacking in top end power and general comfort. I quite liked it despite it's shortcomings - it handles very well, is well built, has a better gearbox and brakes. I thought the Wee vibrated more, but may be wrong.
It felt like the NC had as much lowdown power as the Wee, gets to 60-70 fast enough but then there's not a lot left. However the fuel consumption is allegedly very good, as it the price (new) so it might be the right bike for some. They are certainly selling quite well. I'm looking for a change from the Wee but not sure the NC was quite good enough, might go and try the NC700S when it is released. If you're after a cheap bike, with low maintenance and are interested in going over 70 then this might be a good choice, but for most it's probably a bit bland.