When modeling my Infinities with Qts values of .7 and .48 I noticed a noticeable drop off above 50hz with the higher Q driver. After listening to both I can confirm that. The higher Q driver had very little impact, but better low end extension. The lower Q driver has excellent impact up top and sounds much more controlled (tighter) but lacks a little on the bottom end. However compared to a sealed enclosure it is still night and day.
Mobridge DA2 > JBL MS-8 > JL Audio HD600/4 > (3) Hybrid Audio L3SE & (2) Rainbow Cal25; JL Audio HD900/5 > (2) Morel HCW-10 & (1) IDMax 15