My preference for BTC<->SafeBTC over Maid<->Safecoin is not only for utility reasons but, as far as I know, for the lack of multisign transactions within Omni layer. If implementing bidirectional transactions, between the BTC blockchain and Safe, are already an extremely difficult task, doing it without multisign transactions seems to my impossible.
More than three years ago I raised, in a Spanish forum, the possibility of the existence of SafeBTC as altcoin in Safe. Since then, I keep thinking about it from time to time, and, truth be told, I still can not find a theoretical solution that meets the required security levels in a decentralized manner.
If the conversion BTC->SafeBTC and SafeBTC->BTC are possible, the critical point is who and how the BTC private keys are stored and managed and how a BTC transaction is signed without the private keys being leaked. If someone solves this points the implementation of a decentralized conversion is perfectly possible.
Among the different solutions that I have thought of, is to divide the private keys into different groups. Encrypt the private keys and keep the private and encryption keys divided into different groups and use a third group to regenerate the private key at the time of signing. Use the Shamir Secret Sharing Scheme to divide this keys between several groups, etc., etc… But in the end they all collide with the fact that one or several strangers, who are not reliable, must sign the transaction which gives them access to, at least, one of the BTC private keys.
Maybe someone intelligent and with extensive knowledge of the BTC comes up with some solution @mav