Allrighty, with 10+ hours in 2 different 500-series Citations AND 50-something hours in the 336 Skymaster without any of the planned mods (whatever the excuse - they aren't installed and I'm moving on) the results:
In a descent, with a tailwind, tired old past TBO engines at full power, half tanks, one person, one seat, and it has just been washed, I'm having a hard time seeing 140 ktas in the 336 BS Bomber - an appropriate nickname for the comment I made earlier. Even with the mods, I doubt we'll match even the Riley Rockets.
Good grief, our flight school's Warrior with a 197 h.p. engine is faster (~145 ktas at 65% power).
Fully loaded with fuel and cargo, I can still be off the ground in about 4-500 feet. I haven't explored just how short is possible yet.
For the Citation, no contest. It does take more runway, especially single-engine on a hot day at a high altitude. The control forces, especially on the taxi, are surprisingly light. The effective useful load is nearly the same as the 336 for about 4x the operating cost, but you get there 2-3x faster.
I also think the designer gave up. The FAA recently (Feb)designated the 336 to be a vintage airplane with only 9 remaining in flyable condition.
Fly SAFE!
Jedi Nein