Oh OK I thought I read somewhere that you will lose some pressure with csst because the inside isn't smooth, so that's not the case right?
Wrong. All gas pipe will lose pressure along the gas stream based on the inlet pressure, pipe size, fitting placement, pipe wall conditions, pipe material, and most importantly required gas flow. Your question is meaningless without knowing what the load is at the end of the 26' of pipe.
In general though, on a run of that length you should fine on flow if you upsize your pipe one size from whatever the inlet size is on the appliance. For example, if you have a 1/2" inlet on your appliance, go with the next larger pipe size over to the appliance and then reduce just before the appliance. That should work on all but the longest lengths of pipe (say 100 feet or more).
If you can use black pipe, I would do so. I'm not an expert on CSST, but I've been doing some research on it for work. The national fuel code does talk about CSST, but with little detail. It does specifically say that CSST can only be installed in accordance with manufacturer's directions. 2 things I have noted on the CSST brands I have studied.
1. All require the installer to be licensed by the manufactuer. So if you aren't, your installation, even if it's perfect, suddenly is in violation of the fuel code.
2. All require grounding to help mitigate lightning strikes, which have caused some fires in CSST installations.
My understanding, so far, is the CSST has to be grounded with a minimum #6 wire to the buildings main electrical ground.
As long as you go with a currently licensed installer you should be fine. The documentation I've seen from Pro-Flex (for instance) says the installer has to be licensed by them. That means someone with a wardflex license couldn't install Pro-flex, I guess.
Like I said...I don't know much about it yet, but what I do know worries me a bit. Black pipe is the proven solution.
Phil