Both of those kits are about 10 years old or so. I have heard both.
The Spitfire was someone else's build, not the designer's, so you can wonder if something was missed. According to the design, it was supposedly built faithfully. That said, I feel the tweeter needs amplitude reduction. I can't estimate or guide further until that is resolved.
The Blues kit is a good entry level design that does not cost much, and can be cranked on if desired. I find it to be benign and neutral, to the point where clarity and transparency are not it's best qualities. It does the job applied for and does it well; smoothly nonfatiguingly.
If you are stuck on a HiVi woofer, want good polar response, and can spend a little more, than my Nephila design is likely where you should look. I felt they were very good when I built them 8 years ago, with props from the judging at MWAF, Jeff B going out of his way to write a review, and now some new information that has come to light in the past couple weeks.
They passed hands through Robert "Brian" Clark to Bill "4thtry" S, who is now the current owner. Bill has recently been guided into nailing his polar measurement technique, and wanted to know what made these sound so good to him.
To sum it up, their measured directivity is absolutely fantastic, and measures better than anything Bill has measured to now over the last few years. That said, at one meter there is a bit of a bump in the treble, but measured further away it disappears.
If I can figure out how to scan and post the paper copy images, I will do so.