I do like the Canoptek Acanthrites also, but they would never work as a centerpiece. They would look amazing with an all Canoptek/Cryptek army, but they won't really stand out.
I do have a couple of reservations. The first is related to the second. The first is price. The Tomb Stalker is 41 GBP and the Sentinel is 48 GBP. This is roughly 66 and 77 USD respectively. This really isn't that bad, considering it would be a major component of the army. I could get over it if not for the second reservation. Quality. I have never purchased a Forgeworld model with satisfactory quality. I've purchased some obvious recasts off eBay before... with amazing results. Forgeworld can't even match the quality control of the bootlegger recasters.
I'm hesitant to buy from the recasters. I don't like supporting that sort of thing. At the same time, Forgeworld is difficult to buy from for an American and sells a suspect product, so I don't really want to buy from them. I REALLY wish they could work out their quality control issues. On top of that, the recasters represent a 20-30% price cut with free shipping.
I'll make a decision after Christmas most likely. Stay tuned.