Kind of depends on how you balance the woofer, and placement. < 50 Hz would be my preference, but if you need punch and R&R value, I'd suggest making the cabinet smaller to give it a bass bump without sacrificing more efficiency.
The design is aimed at small to medium sized rooms, so may just settle on 0.7- 0.75. 2.5 ways often have slightly too much output round 200-350 so can see I may hit a problem with a sealed design with room placement issues.
The crossover point of .5 woofer is fairly critical
The crossover point of .5 woofer is fairly critical
There is for and against for this. For is that the box is generally physically smaller and transient/phase response is better. If you have high F3, then you have poor efficiency in the bass. You have to throw a lot more electrical power at the woofers to achieve the same levels as a system with a lower F3. Both the amplifier and woofer become less linear as current increases.
Personally I prefer ported boxes tuned low (25-30Hz) but that probably has a lot to do with me almost never using woofers larger than 6.5" and being a basshead. Both voicecoil current and cone excursion are minimised which gives clean bass compared to EQ'ing a sealed system with a high F3 to hit the same in-room response. The difference in transient response is completely unnoticeable tuned that low IMO. If you're not a bass head, then EQ it down and achieve even cleaner bass.
Ordered the Scan's last night. Haven't ordered the tweeters yet, still undecided. Will start building cabs in a few days