I doubt Lionel when they developed TMCC had the idea of ppl retrofitting older engines, it was because they still primarily relied on the pullmor. They wanted to sell new engines with this gee whiz system,same way they introduce new and improved versions of legacy in engines they had done w earlier versions of legacy or TMCC. Lionel to their credit semi opened up TMCC when they put the DB9 port on the base,but they never made open the protocol between the base and the engine, which would have allowed 3rd party firms to build compatible decoders and bases ( in a sense, it would been like DCC that way). Thus you had to still buy the Lionel base . Also note that Lionel only licensed TMCC boards to other makers,, never legacy . I am not clear as well whether DCS can fully control Legacy engines through the serial connection, or if it is limited to TMCC level either.
And before claiming I am bashing Lionel ,I am not, just saying their decision was based on a model where they controlled the technology to their advantage. HRJ is right, they could have chosen DCC&made it work with AC motors.
MTH on the other hand went totally proprietary,Atlas had to in effect buy part of the business to be able to produce PS 3 engines. They made money with the control system, it meant you were locked into PSx engines from them ( since no one else could make them).
One thing for sure, if we had DCC in 3 rail we wouldn't have a situation we do,where we dont know when the 2 prop systems will be available. Not to mention we wouldn't have the cost of 2 seperate control systems and issues like older boards no longer are available, in DCC, it is easy to replace an installed controller board w a range of choices. You can in theory lose manufacturer extensions,but you still have most of the capability.
Obviously it doesn't matter , we have what we do. Base 3 at least allows seamlessly tying the various pieces together of Lionel CC.
So the answer with CC is the same as it has been for decades, to not be tied to one co for CC, buy both systems.
