Otos will not disrupt your carpet, no matter how poorly rooted it is. They are very gentle swimmers, and I believe they generally prefer to suck on larger leaf plants. My otos only go to my HC carpet to rest, and when they do, they elegantly balance on their pectoral fins. I had no problem with them disrupting the carpet while it was taking root.
If you want a cory but don't want uprooted plants, try pygmy cories! They're too small to mess up your scape. As a plus, they are absolutely adorable. Their swim style is a sort of wobble, and when they get together to school it's just the cutest, bunch of wobbling bug eyed guys.