HW.
In the case that you allude to I think the big issue is Motivation. This new contract will need to get up and running quickly to meet handover deadlines etc, otherwise finacial penalties may apply. If staff were just paid the going rate - rated or unrated - there wouldnt be the urgency from the employee to get all his/ her ratings quickly. No matter how well intentioned an individual may be within a training system, other factors come to bear and performance can suffer. In a case such as the contract that I think you are talking about, if one or more dont validate, then this may put an unacceptable pressure on an alrerady pressurised roster. After all the roster will be made up of people all starting the job fairly close together with a wide range of experience and differing expectations regarding the Modus Operandi (all very stressful). It wont initially be one based on the usual hierachy of experience and standardisation. So if you are confident in your own abilities and "trust" that the training system will give you a "fair go" the issue of training pay shouldnt worry you. Get there, get trained, pull your weight on the roster and get the just rewards. As far as I know TP as such is not advertised too much in the civil ATC world unless you are an ex mil controller looking to crosstrain. And then its often done as many Mils in their late 30's alrerady have a pension coming in when tey leave the service (eg RAF FLTLT APPROX A$25000+ after 16 years service).
Good luck if you throw your headset in the ring.
DogGone