BASE is now EXCLUDED from HCCMIS Atlas Travel Insurance
After reviewing the fine print of HCC's Atlas policy (at pg. 12, paragraph 27 of ‘Other Exclusions’ found here) BASE jumping is now expressly excluded. I called HCC to have Brandi Peyton clarify (she's a sales rep for HCC who previously posted on the travel insurance thread). She's no longer with the company, but a supervisor named Ron confirmed that HCC no longer covers BASE related injuries at all. He said it became prohibitively expensive after receiving multiple six-figure claims from BASE jumpers in the last year alone. Ron can be reached at: (317) 262-2132 and is willing to answer jumpers' questions. Again, this pertains to any policies issued AFTER April 1, 2013.
He recommended trying http://www.insuremytrip.com, an online brokerage that apparently allows side-by-side comparisons of sports-related policies, but I haven't checked it out yet.