Lemmini doesn't provide the option of untimed bombers to the player though. I believe NeoLemmix is the only engine that does - all others either have timed bombers only (Lemmix, Lemmini, Cheapo, SuperLemmini) or instant bombers only (Lix).
However, the fact that in these conversions, it was specifically chosen not to use timed bombers, gives weight to that perhaps they should be removed altogether. Another consideration is that Lix recently went from timed-only to untimed-only, and it seems to have been widely appreciated.
Indeed, GeoffLems is the only NeoLemmix pack I can think of that uses timed bombers, and this too was a conversion from another engine (Lemmix). Even packs from authors who have generally shown a preference for traditional features (eg. GigaLems) have tended to use instant bombers.