I suppose they'll get the job done if everything goes right, but it often doesn't. Obviously, a smaller 2-blade head would penetrate better. I also think there are other 3-blade heads that would penetrate better, the Woodsman, for example.
The Montec and Hellrazor are short/stubby heads and don't have the mechanical advantage that a Woodsman has. They were designed for wheel bow shooters, and, given their more efficient and generally higher poundage equipment, they don't have trouble pushing those short heads through critters. Not as easily done with a low weight trad bow.
One can find several examples of anything, so I'm sure someone will provide anecdotal evidence of their lethality on deer size critters. Wouldn't be my first choice though.