The fact is that the Trezor is really not built on a secured microcontroller, however:
- the possibility of security holes does not mean that there are some
- and more importantly the use of secured microcontroller does not guarantee the absence of security holes
Thanks for the summary. I don't want to argue in detail against the Ledger because I'm involved in Trezor, but the main difference is in a display. The main mission of TREZOR is that you can use TREZOR easily even on untrusted computer, because you see what you're signing.