HBAR's have been around awhile now. Some guns ship with them. Call Ty and check availability
It sounds like you are regretting your choice, I oredered mine with a heavy barrel just because I thought it looked better than the LW versionI have mine in 16" HB. I recommend the LW barrel unless you are shooting a high rate of fire. The XCR is full floated and even a pencil barrel will be accurate compared to the HB version (my oversight when I got mine). If loger range accuracy is your goal, get the 18" barrel, or the 16" HB if you plan on cutting it to 12 or 11".
Currently they do not have a fluted barrel option afaik. All of their current offerings (and offerings coming soon) are listed here: http://www.robarm.com/products.asp?cat=10Question related to heavy barrels on the XCR: Does RA have a heavy barrel fluted option? Benefits of increased surface area for more cooling, less metal for weight savings, and it just looks damn cool. Is this/will it be an option?
Note: I just found this forum during my "thinking about getting an XCR" research and I'm amazed at the posts, feedback and interaction from the manufacturer (Alex and Terra)...definitely a huge mark in the "buy the XCR" column!