The Rapid is a bike I know pretty well, though I don't own one. Back in '10 when I bought my current bike (Spec. Sirrus), it was the other one I was considering, and I tested it extensively.
A couple of comments.
First, the Rapid is a 'road bike'; the only differences between it and e.g. the Giant Defy are the flat bars, and the fact that the top tube is properly lengthened a couple of centimetres for a given size (to accommodate flat bars vs. drops).
Second, given that, given your intended uses ("for keeping fit and training for sprint triathlons (first one in June), as well as occasional commuting"), given that you want flat bars as opposed to drops, and assuming it fits you/you like the way it rides/handles, you can't do better for the money.