I am not partial to any brand any more. I have the parameters for the speakers so I was not so concerned in that regard. I'm not really intimidated by the crossovers it's just something I haven't had time to read and learn about yet. It all takes time and it seems like I have less and less of that anymore.
The 5" subs are neat but not really useful for much. They worked in my build 10 years ago but don't have a broad use fullness outside of that specific scenario.
Here is the standard (and oversimplified) method how a DIY speaker is designed. First build a cabinet based on the T/S parameters. For example, build a 2-way speaker using the Utopia 6.5" mid woofer and the tweeter (1"?), using the T/S parameters to design an appropriate sized cabinet for best bass performance. At this point the cabinet doesn't have to be finished.
Next, mount the drivers, and measure each individual driver's frequency response and impedance curves. From that data, choose appropriate crossover frequencies and roll-off curves, etc. This requires a measuring set up, measuring software, and loudspeaker crossover design software. It costs money and it takes time to learn to use it properly. If you can find a DIY speaker builder nearby who has the rig and the experience, maybe you can interest him in helping on the project.
If DIY appeals to you, but you don't want to go whole hog on the measuring rig, there are good kits available. The design work is already done, you build the cabinet and assemble the crossover. See Madisound, Parts Express, and Meniscus for good kits.