For posing and shit, yeah they're just about as stable as an action figure can get. I've only had issues with Roll, she's a little loose for whatever reason but I haven't any issues with the others I own.
Oh that. I believe they confirmed Ultimate X was going to be officially released from that photos. But the GBA Zero that I own is the model kit from Kotobukiya, it's a snap together kit exactly like a Gundam: http://www.hlj.com/product/KBYKP-177/Sci
The kits are sooooooort of in scale with the D-arts, but might not look correct proportion wise.
That's good news. I was a big fan of the Megaman X games, but I liked X more than Zero. Is there a figure of the Megaman Zero Figure? The one from the GBA games? I believe I saw concept art of a D-Arts somewhere but I can't find it now.
Forgot to mention that ZeroV2 is quite a solid figure, if V1 is any indication, despite the paint issues I've had with mine though I'm not sure how widespread the problem was. Search around and see if you can nab them on sale…I got lucky and got FA X And Classic Megaman from collectors that wanted them gone.
X Figures are quite stable. I haven't found any issues with them. Best one I own is Vile, he's the one that comes closest to Figuarts-like quality. X isn't bad, but he kinda suffers from the limb swap gimmick he shares with Full Armour X. It's nothing crippling, but mine seemed to have gotten loose overtime. I have them all though, except for Bass and Zero V2.