Jim Dwight: I'd like to have a Festool Domino but I don't need one and I don't want one as bad as many other things I will buy first. I have a hollow chisel mortiser which will do, if anything, bigger mortises than the Domino but takes enough longer to do it's thing I don't use as many mortise and tenon joints as I would with a Domino. I don't see a similar argument for a Festool dust extractor. I bet it is nicer to use than my Rigids but I use the Rigids whenever I need to.
Jim, I too have a mortising machine, a really nice Powermatic Benchtop unit (I don't recall the model off the top of my head). I have continued to use it for larger, heavier duty mortises while I pull out the Domino for the smaller ones. It's a system that works really well for me.
I fought myself tooth & nail about pulling the trigger on that Domino though. It cost more than my PM mortiser! But I've found that the mortiser can be finicky on smaller items, while the Domino really shines there. That's exactly why I opted for the smaller 500 series model. I now have the full spectrum covered.
And,of course, I also have my set of mortifying chisels for those times when nothing else will work. For example, I just built a hall table with sculpted legs and much to late, I realized that I should have done the mortises while the stock was still square. Because of the curves it wouldn't work in the mortiser without some type of elaborate jig. Nor would the Domino work because of how close the curve started to the mortise, there wasn't room for the tool. So, out came the chisels. And actually, it was fun chopping them for a change. Over the years I have drifted more & more towards the Neanderthal camp. Although, I'll never go electric free.