Issues I am aware of: Lack of demonstrated and extensive testing (from my perspective, this applies to proposed changes from ABC also). Also two of them were rewritten, not originals.
Was OP_GROUP also rewritten or was that an original? Does rewritten mean edited for errors or different functionality?
OP_GROPU is a new proposed opcode. And it is not approved yet, and not under consideration for next upgrade. Maybe in 2019.
Sorry just saw this. OP_GROUP is new. Rewritten I think means basically bugfixed but with respect to security/testing, that makes it effectively new.
