The Apex is supposedly comparable to the 105 groupset and Tiagra is at least one level below the 105. I actually have the Deore on another bike but to me, the Apex shifts much better. One other thing is that on the Sirrus, Specialized is using the sram SL-700 shifter. I don't know if you have used sram flat-bar shifters but it can be cumbersome because you have to shift up and down with your thumb and one lever is offset further back so you have to reach further back with your thumb to shift down. I don't have big hands so I don't like it at all. In that respect, the Shimano rapidfire shifters are much better. Anyway, I replaced the sl-700 shifters with sram double tab 2x10 and there is no looking back. Good luck with the 7.7. I'm sure it will be just as nice.