I'm considering ordering the R15. I simply enjoy handheld receivers! I own the R30, which is still a gem of a receiver, with the exception of its aging display. I primarily monitor airband and some HF with the R30.
Though to justify the purchase of the R15, I would need to be convinced that the R15 is a decent upgrade over the R30 on the airband. If that is so, I may even sell my R30. I own a couple of other HF receivers, and I'm not interested in D-Star in the R30. Also, the P25 and NXDN capabilities of the R30 are covered by my recently purchased Uniden SDS150, along with DMR. Oh, and regarding the SDS150, it's my experience that it performs similar to the R30 on the airband! So that's also something to consider.
Lastly, I'm also awaiting delivery of the Alinco DJ-X00T, which is also a great airband receiver, and brings DMR, D-Star, NXDN, C4FM (System Fusion), and dPMR digital modes, plus data modes like AIS and ACARS. So maybe I don't need the R15, but maybe I do!