This is a really good thread on the subject you're asking, lots of ideas - Shimano vs tektro road calipers

I also found the review that in cycling weekly that talks about how the brakes don't have good initial feel. The same review goes on to say the stock wheels are on the heavy side and your shifters are claris so tiagra might be an upgrade path - I added that last bit.

I think your frame has the carbon fork so the frame is shared throughout most of the lineup which means the frame is worth putting money into.

Make sure the brakes are setup the best they can be before needlessly throwing money at the issue.