aftermarket pistons have the HUGE advantage of generally have deeper valve relief pockets, giving you much more options for cam timing.
Geeting good midrange will be tough if you have no room to run the cam timing you need to get there.
You are both saying the same thing, that it's better to remove part of the gasket when trying to add compression, rather than removing the material from the head. You get more compression rise from the gasket than you do by milling the head.
milling the deck is certainly do-able, but for most it's not a viable option, as with todays one piece cylinder/upper case half it will require the complete dissasemble of the engine.
I personally would never run squish as tight as .023, but I feel safe at .027-.030 with stock parts. From what little I have seen the factory is still a ways from that stock.
Increasing the squish won't add 10 hp, but neither will splitting a gasket or milling a head. It's all little steps to make it as good as you can with what you have. Tightning up the squish will help to keep the non combustion chamber area's clean, and help keep ping from having a far off spot to start.
basically no matter where you take the height from the deck or the headgasket, or if you mill the head to get more compression, your limit will be the squish you feel safe running, and the P to V you feel safe with.
I had .003 positive deck with my g1K motor. Not the way I planned it, but using a thicker gasket made the squish come out to .027 like I wanted, while keeping safe P to V numbers. The P to V numbers turned out to be way safer than I had orignally hoped for, as the compression was so high it pinged like hell, forcing me to change the cam timing to more top end biased LC's to help get rid of the cylinder pressure at lower rpm's.
The 5 valve R1 motor is not blessed with huge ammounts of P to v, so when you go splitting the gasket and mill the head, you won't be able to run the LC's that would work the best on these motors, unless you have aftermarket pistons with deeper dish's. At least that is my understanding anyway.
