I have the domino 500 and the lamello Zeta P2 biscuit joiner. I have to say, ever since I bought the lamello I haven't been using the domino nearly as much. The only time I break it out anymore is if I can't use a biscuit because the wood piece is too narrow, pocket screws from the backside aren't applicable for the piece.
The fact that the lamello Zeta P2 can use the cam locking biscuits, and tenso clip biscuits has changed up a lot of how I build (depending on the application of course). But for paint grade I barely throw a clamp on anything anymore. I just glue it and throw tenso clips/ clamex biscuits in there to hold the seam tight while the glue sets up. If there is a tiny gap in the glue joint, it gets hit with bondo anyhow.
Stain grade on the other hand still gets the clamps unless one side is not seen and the clamex biscuits can be used. Those things draw so freaking tight with the proper set up that you don't even need to put clamps on it. Obviously, if it's seen on both sides this won't work as you have to drill a hole on one side to access the allen key.
The biscuits are expensive, but I build that into the cost of the job if I know I'm going to need to use them.
It's also great for field work.