My latest bike, the Giant TCX W, came with a SRAM double. My other roadies all have Shimano, and mostly triples. I do not see a big difference in the Rival vs the 105 except that the brakes are more comfortable for my smallish hands. I still ride one then the other with no problems. My take on it, it is down to personal preference. If you love the bike and are ok with the SRAM, go for it. I wouldn't let that deter you from the one that was speaking to you.

P2