All above theory ?
As an owner of a number of aircraft I have nothing but prase for the Robin DR400 aircraft but having owned two of them over the past 20 years ( the Robin is my toy )I would never think of using them as a trainer.
There is nothing at all wrong with the aircraft , it is the total lack of product support from Robin that is the problem and with the very lackluster way that they supply parts my business would simply go broke waiting for Robin to produce the bits so that I could fly.
I did take a look at the PA-38 , I like the aircraft as a trainner but the spar life is the major issue.
The life extention program has yet to get past the CAA and will no doubt cost a lot to do so. This puts the PA-38 out of the running due to retun on inital investment.
It was with some regret that the only aircraft that will fit the bill is the Cessna 152 , product support is first class , there is no spar life limit and with such a large world wide fleet it will be a very atractive for a re-engine program when one of the new diesels comes on line.
It is a great pitty that the worst of the three aircraft to fly is the one on which all the numbers stack up but at least I will be in a position to offer training aircraft long into the future unlike the vast number of companys that have fallen to the " interesting" economics of light aviation.