Between the better half and myself, we currently own a CRF230L, WR250X, KLX351, and BMW G650X-country. We just sold my Husky SM610. I have to agree with you that the 230L is super easy to ride on difficult trails, and that can be a big benefit. It's light weight, and low stature make is easy to handle, and it requires almost no maintenance and is super dependable. But for us, that's pretty much where the advantage stops. Neither of us particularly likes the bike. But my husband keeps it, because as a novice trail rider, it inspires confidence. Yet he complains almost every time he rides it!
When he rides the 230L, I ride my KLX. The KLX goes over washboard, ruts, and washouts in luxury, while the little Honda bottoms out and rattles your teeth out. The KLX is pretty smooth, while the 230L vibrates you to death.
Then there's the WR. It runs smoother than the KLX, but for me the powerband of the KLX is better for the way I ride off-road than the WR. You have to keep the rev's up on the WR, but the KLX can be lugged and not complain. The WR suspension is stiffer. I'm super light, so I find the KLX works better for me suspension-wise off-road, but the WR would be better for heavier and more aggressive riders. The WR seems to be higher quality than the KLX overall, and if I ever get down to one bike, it will be the one. But for now I like it for pavement and fire roads, while the KLX is my off-road choice. We prefer the bigger bikes (although my 610 is now gone) for pavement and the occasional smooth fire road. They're too heavy to be fun off-road.
Powerwise, any of the bikes I've mentioned will blow away the 230L. A WR would be a nice step up for you, but the KLX is worth considering too, although I definitely recommend the 351 kit if you get it.