Well, I found these today over lunch. After opening my first one, I decided that he is much better than I was expecting so I went ahead and opened the other one I bought.
They match up pretty well with the K-Mart Clones in color which is nice (I wasn't expecting that after seeing that the Bly/Evo paints were off-key). Also, it feels like the joints on these guys are stronger. Compared to the AT-TE Gunners I've got, the 501 Clones arms stay in the sockets much better, which is a nice surprise.
The red stuff on the feet is a little lame, but I guess there is nothing I can do about it.... I still wonder why they did that since the 501st were pretty much only on Coruscant from what I understood.
The helmet is definitely removable, and the clone underneath still has that "vacant" open-mouthed stare that the AT-TE Gunner had. I guess I like the removable helmet, so it's a plus.
Despite the limits of the arms on the #38 sculpt, they are still pretty cool Clones and I'm glad I found them.
And, just in case Hasbro's reading... even though I've got 5 blue clones, I'd still be willing to buy a few 501st repaints of the #41 Trooper to fill out my squad!