If you know Chekhov, she sticks around for the manga cases. Gosho's original intent for DC is to be able to write mystery; if I interpreted his interviews correctly, he thought of the mystery concept before the plot. I honestly don't think Gosho will be dramatically changing that anytime soon, so some of those suggestion, however much I agree with them, are in vain.
Personally, I don't like mystery all that much because I'm an idiot who can't deduce anytime \o/. I'm here for the plot. Sure, the plot has the whole "find evidence and deduce" scene, but I love the big reveals. I haven't seen an arc that just came to me as "bad" (unless I start watching the infamous Bourbon arc), so... How can I put this? I don't really mind anymore. Plot progression? YAHHSSSS. Poorly written cases and anti-climatic conclusions? Meh.