Truss, I think, is always the way to go. Stronger, lighter, less thermal currents, able to get better air flow and easily closed up with a shroud.
If the truss design was a real problem then Paul's images would not be so sharp. They are so unless he got a good one it does not seem to be a real problem. Surprisingly there does not seem to be a lot of difference between scope builders in the quality of the trusses. I have seen a GSO 12 inch in the flesh and I was surprised at the quality of the truss. It seemed very good and every bit as good as my CDK17 (except for the blue coloured bits!).
https://en.wikipedia.org/wiki/Serrurier_truss
RC's with tubes are a pain. I had a closed tube 12inch RCOS for several years. It sat in the car on numerous occasions at my dark site as it was very easily affected by wind. A truss would have been less affected.
Also the truss gives you something to grab when you adjust the scope on its dovetail for balance and for overall handling installing and removing.
A large tube is very awkward to handle.
Last and of course most importantly, trusses look better! They look more professional.
Greg.