elt fwd
Mine is just under the pilots butt, so little effect on CG.
I'd like to see it between the 'footwells' so it's easy to verify that it's on or off, but you'd need a skookum mount to ensure it stay'd put in a 20 G impact.
Added bonus here is able to remove quickly to a better location, changed batteries etc.( post -impact!)
also easier to wire to your GPS if you have the new style ELT.
Lots of things .....like fire extinguishers etc. really clutter up the forward cabin, but aren't very handy in the baggage area when you need'em!.....and the weight is better off forward as well.