I like the Thielert,, though only have an hour of flying the diesel DA 42.
I think that Contiental would be more attractive, as it has a broader, and more marketable product range right now, and a much longer legacy of success. It is already sustaining itself, with lots of happy customers, and brand new aircraft demand for their engines. Thielert appears to me to have the opposite of demand by new airframe makers (as I participarted in the STC replacement of the Thielerts with Lycomings in the DA 42).
I'm sure the Chinese have though this through for the long term.