I just bought one to experiment with. I got tired of not finding the 930SPX, and so my dealer ordered the 18.5/28" combo (
http://www.rrarms.com/catalog.php?prod=G85325 ). I got the correct magazine extension from Choate (they supply the OEM extensions for the 930SPX, as I understand). The extension installed with no hassles. Since Choate includes an extended magazine spring, barrel clamp and slightly extended follower, I didn't have to order those separately.
The gun field strips reasonably easily. I didn't find mine filthy internally, as some have reported with NIB guns, but gave it a good cleaning and light lubrication (SLIP2000) anyway.
I'm still breaking it in, but so far so good. It doesn't like the light Fiocchi loads that one of my 870s chokes on also, for the same reason- they're sticky on extraction. Remington heavy field loads run in it just fine though. So far all I've used is the short 18.5" CYL bore bead sight barrel. Recoil even with field loads is brisker than I expected with a gas gun. Other than the Fiocchis, I've had no failures or hesitations with it.
With the magazine loaded, you'll want to be careful of the bolt release button on the right side of the receiver- it will release rounds from the magazine as well. Nice when you want to unload the gun, a pain when it dumps a round onto the follower when you don't intend for it to. IMHO that button sticks out too far, and is unshielded.
The design has a bolt return spring tube that runs almost the whole length of the stock. That means it may be a hassle to shorten the LOP any. I haven't challeneged any of the 'smiths I know with this one yet, the factory 14" LOP seems to fit me OK. And it has a fairly decent recoil pad from the factory.
OAL with the 18.5" barrel is 39", and on my cheap spring scale, the weight with magazine extension comes in just shy of 7 pounds (empty).
That's it so far...
lpl