disagree on pid kit only.
the full on duino mod is way better for one primary reason. power steam or whatever they call the thing they do with the steamer. it takes the sputtery slow and weak steam wand and makes it actually functional.
also the "adaptive" settings you can do on there let you basically never have to "dial in" a shot. throw any random (still decent q and paired with a good grinder) beans on there and you get a shot thats very drinkable. For lattes and stuff where you are hiding the coffee in milk anyway this is like still better than 90% of what you can get from the coffee shop with the 20k$ big iron and 0 effort. and when you do have that special bag that wants the extra attention and straight espresso you've got all the controls and presets and shot tracking.
if you are gonna try and do home espresso you already have an involved hobby, if you are gonna mod your machine you are already pretty hardcore about your hobby... you might as well go all in at that point