Unannouncing achievements is not going to happen. Stocking up on bile when players get high-point achievements is a risk. You're making your throwable very situational whereas pipe bombs/molotovs are infinitely more useful in non-Tank situations. People don't always have to buy Tanks right when they get the points to do so...and I'm not sure why so many people do. I don't mind increasing the bile bomb cost, but not up to 20-25 points. Since I incorporated server-side item purchasing stats (remember that google docs thing I posted a while back?), vomit jars were purchased a total of 29,814 times whereas molotovs 139,348 and pipe bombs a shocking 3,977 times (not surprising since people just buy gas cans to disperse hordes)
Also, red Survivors on black and white was put in there to let Survivor's know they're teammates are black and white, so that's not going to change either.
And yeah, No Mercy 5 is also a map in which the Tank doesn't spawn in. Thank Valve for their laziness.