My thoughts
Here are my thoughts which I went through before I recently renewed my agreement with NJA (subject to all the flaming I shall receive). I have had a share in the Excel since the early days of the Excel fleet and was up for renewal last year and did an analysis of CS and NJA. Both are great companies, but the difference depends upon your (or your bosses' friend's needs). BTW, I was (and remain) very happy with NJA (and its pilots) but since it is a large expenditure I always look at my options. I did not consider a local operator for many reasons.
Basically, they are the same price. A few hundred dollars less per month for a share in a CS is not a material difference in the overall magnitude of this expenditure. Therefore, price was not an option.
I fly several times pre year to a remote airport in the Rocky Mountains (I live in the Northeast). In my opinion, CS did not have the coverage and support in the remote areas of the Rockies, however, CS is expanding its coverage. At one point, it charged extra to fly to the Rockies (so did NJA in until the late '90s for "rural" airports). This does not matter on a routine flight, but in the event the plane sent or scheduled for me encounters mechanical issues, how long does it take to get another plane to me? It has happened twice, and the answer is less than 1 hour difference in departure (one time I got a Falcon 900 the other a G-IV -- if I could have only told a few friend I would have extra seats). I have a friend in the same Rockies town who is with FO, has had similar mechanical issues and it has taken 4-6-8 hours for another aircraft.
2nd big issue -- how often do you need an a/c larger than the XL. Once or twice a year I need a larger or longer range aircraft. Even though it is prohibitive on at the interchange rate (for short flights), on transcon flights it is less expensive for me to pay the premium to upgrade to a Citation X and arrive sooner, than to fly the XL. Other than around peak days, I have not had a problem upgrading. At CS, here are no practical upgrade options since the Sovereign is just coming on line and the will probably not have enough of them to routinely grant requested upgrades. And sometimes you get upgrades just for NJA scheduling convenience or because there may have been a mechanocal delay or another issue on a previous flight. NJA tries to make amends with a larger a/c. A few years ago we had 3 various delays in 1 month -- then I got a call which said our next round trip would be a guaranteed upgrade to a G-IV as long as it wasn't a peak day. Guess what, we took another family away with us. I wish I was inconvenience more often. It is the NJA version of the old days of getting bumped commercially, getting there 2 hours later and getting 2 free rounds trips. Between the goodwill upgrades and its scheduling upgrades, I have probably had 3 G-IV flights, about 6 Falcon 2000 flights, and numerous Citation X flights. And, when they put me in the C-X on a flight to the Rockies, I use about 1 - 1 1/2 fewer XL hours. This is an added "fringe".
I know a few CS owners who are very, very happy with CS. They mainly fly around the NE, and from the NE to Florida, Atlanta, Chicago. They do not need the range or the depth in the Rockies. Therefore CS works fine for them.
NJA generally allows flights to a certain points beyond US borders w/o ferry charges. This includes most of the Bahamas, southern Canada, parts of Mexico, and I believe they have waived all ferry charges to Cabo. The only problems I have encountered are in a a/c by a/c determination NJA will not go into certain "island" airports if the runway is contaminated (a new term I have learned) or for example if the FBO does not have sufficient insurance or other items (this applies to the US as well ... they have denied acess to a few FBOs on the basis of insurance). Otherwise, I have gotten into some islands whose runways undulate, are barely paved and have no taxi ways in the XL, C-X and Falcon 2000.
If you need more info, please do not hesitate to PM me.
I know somehow, someone will find a reason to flame me here.
Fly safe.
P.S. (those who know me on the board know I can be sarcastic so I include the following). No post on the board would be complete without a reference to the NJA pilots salaries. If you want a more "socially responsible" provider, CS pays its pilots more (form what I hear -- I have no first hand knowledge), therefore, it must be more socially responsible than NJA.