New site member DrLycus, now Cerastes (account age 77 days, site membership 76 days) has been giving some vague/catchphrase-crit feedback in the forums lately:
http://www.scp-wiki.net/forum/t-4426238/i-would-like-some-opinions-please#post-3647358
The thing about writing humanoids is that they're held to a much higher standard than most other types. They need to be written realistically and as an object, not a person. A good example would be SCP-029. Of note is that it refers to it as a "she", but its written very clinical and detached.
One problem with your idea is the "X-men Syndrome". If it sounds like a superhero, it might needs some work. Right now, it's just a guy who can change materials around it, no downsides. Its probably a little too early to properly judge it, but I'd recommend thinking about how you can play around with the concept, maybe give it a good downside.
http://www.scp-wiki.net/forum/t-4411874/looking-for-critique:scp-xxxx-gay-trash-man#post-3645993
Well the title pulled me in, so props for that.
1: Remove the references to he and him. It's an object, not a person.
Change this: [one small change mentioned, no other feedback given]
Currently, it doesn't look like they're posting a ton of feedback, but given that what they have posted needed to be addressed by staff, it's something to keep an eye on.