I have flown both the 35 and 36 with the R/X mod. The 36 had the locker also. The biggest problem with the combination is the large increase in side area, which makes the aircraft interesting in a stiff cross wind. The full mod includes increases in gross takeoff, landing and zero fuel weights. However, it decreases the tip landing weight and fuel imbalance limits.
It was my experience that the mod does quite well on the 35. Mostly because the aircraft didn't weight much over the standard limits. It would go to the upper 30's and run along at normal cruise. The 36 was a pig. It would weight #19,500 (the new GTOW) and would only get up to FL330. And you would be stuck there for over 3 hours. In fact it was my experience that in reality the 35 with the mod had as much range as the 36 with the mod.
Now both these aircraft had the -2B engines. It is my understanding from pilots who have flown them with the -2C engines that the 35 will go straight to FL410 and the 36 will go to at least FL370.
The 35 will do coast to coast westbound at least 50% of the time. The fins make them both comforable flyers and seem to help reduce the autopilot problems that the 200 series always seem to have.
One of the biggest issues is the tip tanks. Do not land exceeding tip limit. The extensions always seem to leak even if you are just a little bit over.
Overall, I enjoyed the aircraft. It was nice not having to sweat fuel all the time. Fuel planning took a little more effort, especially when you had a boss that always pushed you to buy the cheapest fuel.
