Aside from the internal floodgate adjustment is there any difference between the two versions?

I don’t think there are. On Pikes that’s the only difference.

Like you have to adjust the floodgate every day! Hardly worth it.

409 probably maybe won’t come with a shock pump as it was intended to make it to go on new bikes, not sold seperately? Only a guess though

So OE only??

409 is OE
426 is aftermarket

the only difference is whether you need an allen key or not to alter the floodgate, and maybe don’t get a shockpump with a 409. Thats it. OE means it was intended to go on a bike, nothing else. Still warrantied