I am on the fence between the MiniStatements and the ZDT 3.5. It will be about an extra 150 dollars for the MiniStatements but I am willing to spend that if they will sound better. Also I am thinking one might sound better in my space than the other. My space in 13 X 16 with a divider in the middle, without the divider the room is 13X30. Here are some pictures of my space. As you can see in my pictures I have to toe my speakers in because of the size of my screen and my sitting area. They don't have to be corner loaded and can come out some but not too much as you can see.
http://img13.imageshack.us/my.php?image=img1581c.jpg
http://img15.imageshack.us/my.php?image=img1582j.jpg
Mike
You ask a tough question, because I haven't heard either of these speakers. I'll try to sum up the pros & cons as I see it:
Both John Krutke (Zaph) and Jim Holtz are very good designers. Don't worry about who might be better.
Both are 3.5 way designs using two RS180 woofers, where each woofer has different low-pass filters. They both are 4 ohm speakers with their lowest impedance down to about 3 ohms. Zaph mentions that his inexpensive Panasonic receiver drives the ZDT 3.5 without apparent trouble, and that a NAD 120 wpc amp does very well. I would guess that the MiniStatement, with the same woofers, will be similar.
The main difference between these two designs is the mid range drivers. I've heard other DIY designs with the Dayton RS52 2" dome and I like it. I haven't heard the Tang Band 4" titanium, but many other DIY people say it sounds excellent. The advantage of the 2" Dayton dome (in addition to price) over the 4" Tang Band would be its better high frequency dispersion. It's disadvantage is its low frequency response, lower power handling, requiring a higher woofer-to-mid crossover point. In the MiniStatement, the Tang Band 4" titanium midrange can go to lower frequencies and has better power handling. The woofer-mid crossover in the MiniStatement is at 400 Hz instead of 850 in the ZDT 3.5. In the ZDT 3.5, there may be (I'm speculating here) audible differences in the off-axis response as the woofers roll off at 850 Hz and as the 2' dome mid kicks in. In the MiniStatements, this transition takes place at 400 Hz where the off-axis response of the woofers is likely to be better.
The inexpensive Dayton ND20 tweeter in the ZDT 3.5 is actually very good if you use a high enough crossover point as in the ZDT 3.5. It is a good choice to use with the 2" dome midrange. Because it is a ¾" dome, it will have excellent off axis performance. The Fountek NeoCD 3 ribbon tweeter is a lot more expensive (it is also out of stock now at Madisound) and may have a "cleaner sound" than the dome tweeter, but I think it will make a smaller difference than the differences in the two midrange drivers. For what its worth, ribbon tweeters usually have noticeably narrower off-axis dispersion than do small dome tweeters.
There, I hope that helps.