Just my $0.05 worth here (corrected for inflation).
I've dealt with older houses over here in the past with 1" x 5/8" timber lath and plaster walls.
You'd be suprised how much control a 4" angle grinder gives you with cutting wood and plaster with the right disc on it.
I've never struck a house yet that has steel laths, but I'm betting with a steel type disc, you could chew through both the plaster and the laths, as long as you have some sort of dust extraction system and a fire extinguisher in case there is dry/flammable stuff in the bottom of the wall cavity.
Although I've yet to set anything on fire with an angle grinder, if you're careful, it doesn't hurt to have things like that there, just in case.
