Regarding detection, I'll need to do some further reading, but I think it's entirely dependent on the formulation. In principle, they should be able to interact gravitationally like anything else with mass and energy. Then again, I could probably design you an interaction scheme by the afternoon, and some poor experimentalist would need fifty years to test it. Regarding consensus, as kind of an outsider to the field myself, I'd say it's getting to the level of "it can't hurt to fund a theorist or two working on it" when it comes to recognition. And, really, the off-chance of tachyons yielding reward IMO trumps 98% of string theory research, and we keep funding that 11-dimensional monstrosity.(2) Humor an old man - last I heard, tachyons were on about the same theoretical footing as phlogiston and even if they were verifiable, the zeroth law of thermo prevented us from ever observing or interacting with them. Has the consensus view moved on that one?