I haven't seen any info on whether there's any effort in transmission to support the bittorrent v2 format [1].

Are there any plans or efforts to support it yet? The major reason is the breakage of SHA1, which causes vulnerabilities like the BitErrant attack [2]. The v2 format switches to SHA256 and a Merkle tree structure.

As long as this is unfixed torrents can't be considered as a secure download method that guarantee data integrity.

[1] http://www.bittorrent.org/beps/bep_0052.html
[2] https://biterrant.io/