25mm head diameter for the ec200 vs 28 mm head diameter seems pretty close, but sometimes small changes can make a pretty big change in feel.
I've had a number of flashlights, from cheap to enthusiast, over the past 10 years and none have failed through nomal use. Dumb things have happened, like me dropping my m43 in a basement and breaking the glass front cover or my kid chucking my Frelux Synergy1 and breaking the driver board, but its never been the light's fault and things were repaired. Flashlights are generally pretty simple if you're familiar with basic electronics and most enthusiast brands are easy to disassemble which opens up the world to repair (replacing switches, glass/optics, drivers, etc).
On the front of emitters, the D4 has been around for a while so you're going to find writings on a variety of emitters that may not be available anymore. IME different stores can also offer different emitters.
Make the color temp, tint, and efficiency vs CRI trade-offs you want, but I wouldn't worry about agonizing over say two warm high CRI options. I don't know their current emitter line, but the choices available are generally pretty good. Emitter size influences beam shape, but in a floody optic light like this it's not going to be a super dramatic difference.