I recently got a mauser with a butter knife bolt handle. I'd never used one before, but found it to be just as fast/easy to use as a rounded handle when using the blade/palm of your hand to work the bolt. I really expected it to be more troublesome but was pleasantly surprised.
wouldnt say its troublesome, just absolutely hate how it feels....guess it feels like less of a solid contact with my palm when working the bolt......may have to leave it for awhile and see if it truly feels better as far as packing but i have a feeling regardless its getting changed....
my wife however runs a bolt with her thumb and index finger and loves bolt handles like this or the flattish dog leg handle of the Rem 600 type rifles