I had around 3000TT, 1500 jet SIC (including 75 SIC in a 500), but zero turbine PIC time when I started flying a 501 single-pilot. I went to SIMCOM where all the training was with a crew as their program (and most of the others) is certified as a 2-pilot 550. The insurance company's original offer was 75 hours with a "qualified" captain (CE-500 type and been to training within the last 12months) before I would be covered single pilot. After negotiating with them for a bit, they then said 25 hours with a qualified captain. What actually happened was that after I flew two trips for about 7 hours with the qualified captain, we talked to the insurance company and the guy I flew with gave them a report of my proficiency and they said that I was OK after that to fly single pilot.
It's an easy jet to fly single pilot. We usually fly FL310 - FL360. It will go higher (I've been to 410 in another 501) if you are light and are trying to get more range, but it really likes the low - mid 30's. Plus it's an older airframe with a single door seal and we don't have the quick-don O2 masks. Normal cruise is 345KTAS with 1200lbs first hour 1000 lbs second hour, 900 the third, then land.
As for the Sierra engine mod, our company was excited about that for awhile but the problem is after a 1.5 million upgrade, you have a 30 year old airframe with new engines. In our experience we have had little trouble with the JT-15D's (other than being inefficient compared to newer engines) and most of our maintenance issues are airframe-related (pressurization problems, landing gear issues, windshield cracks, etc.) The numbers don't lie and Sierra has apparently made quite a performer out of the 501 with the Eagle and Stallion conversions, but for 2.5 - 3 million I would want to look at something newer. The good thing is that you shouldn't have too much trouble finding someone who can work on an old Citation.
Our's is a 1978 501 with 6000 hrs on the airframe. It has the Sierra 3-place seat mod on the inside which takes the aft potty and coat-rack out and puts the 3-place seat further aft than the original single chairs. Gives you a ton of room inside, much more so than a 550 (one of the reasons our company is having trouble finding something newer with comparable room). Ours has anti-skid (the old system - off until you start the takeoff roll, off before you clear the runway) and no T/R's. T/R's are kind of a waste on a 501 in my opinion since you land so slowly anyway by the time you get them deployed, it's close to 60kts and time to go to idle. Of course the ability to go to zero thrust is nice, but it's also nice to have the extra load capacity, especially if you don't have the ZFW increase service bulletin as we do not. Our rough runway limits are 3500' dry and 4500' wet.
While the 501's aren't as long in the tooth as the 500's, they are getting some age on them. You aren't going to go a long way in the 501, but it will put you out of the weather on longer flights (as opposed to turboprops which a lot of people also consider when looking for a 501) and it's suprisingly quiet (inside) for an old jet. If you could find a lower time 501, RVSMed, with upgraded avionics, and nice paint and interior, with engines not long out of overhaul or hot sections for around 1 - 1.2 million it might be a good deal.
As for the Citation Service Centers, Cessna would really rather these older birds just go away from a liability standpoint, so the older Citations get HAMMERED when you bring them into a Service Center. Also, I've heard of some centers with limited mechanics that have experience on the older models (they have a high turn-over rate) and you may be paying for their learning curve. It would be nice to acquire one that had been maintained by a Service Center, but I wouldn't take ours there unless it was 100% necessary (Sierra mods don't exist as far as they are concerned, Cessna windshields are the only ones they recognize, etc.)
Overall it's a simple jet (if there is such a thing), easy to fly and maintain. Seems like there are several on the market currently so maybe you can find a good one - good luck.
