I have a few loops of 16" .063 left that I will use up on the 026. But setting up my "new" 261 I would prefer the longer bar and with the Stihl 23 Pro and 33 X-Cut chains, I see absolutely no reason to stay "married" to the .063. Once what I have is gone, the 026 will also get an 18 x .050.
But, as I have seen, finding a true NK bar for a Stihl is definitely a challenge. I do know the Light 04 and E bar are both thinner than the Tsumura FV (.166 vs .175), so I guess they qualify? I'd like to find something "nicer" if I can though...
I know alot of guys are running the Stihl 23 and Husky 33 chains on a standard bar. But I haven't heard for certain if they are able to use that bar for the full life of the chain. I'd be very disappointed to learn the hard way that I can only use half the chain life, especially if a little effort in preparation can prevent it.
On the flip side, I do have a bench sander, and access to a full machine shop, so it shouldn't be too difficult to shave .005 off each side if it came down to it. But then if I ever had to replace the nose, I'd have machine it down also. And with that comes the question of rivet strength amd such... Just a situation I would like to avoid completely if possible.