Hi Pyksel, welcome to GH. There are a number of split-ergo keyboards. Most don't exactly have the same curved shape of a MS Ergo. They tend either be flat and split, or super funky like a the Kinesis or the Maltron. Search for either of those terms and you'll see what I mean. As an intermediary, a number of folks are looking forward to the Truly Ergonomic keyboard, but they are an upstart and have yet to deliver their first board (see the thread on them here, or visit their website, trulyergonomic.com). Part of it depends on how far out of the box you want to go in terms of layout. It also depends on what your priorities are for ergonomics. There are a number of issues involved with keyboards, some of them have to do with hand position, and others have to do with key action. Some comprehensive ergo boards like Kinesis and Maltron deal with both, but they are not cheap, and may not be necessary for everyone.
I've used MS Natural keyboards for years, and I do like the split layout, but eventually the rubber dome switches really bothered me. Since I've gone down the mechanical path I've found the feel of the switches actually keeps my hands better engaged in the typing process and alleviates a lot of physical typing stress associated with pounding on rubber domes.
