Actually two DL1608's and a cheap (or home made), passive, analogue summing device would give you a 32/8 I/O mixer (this concept has been discussed before on here or the old Mackie forum). If you already have a DL1608 then adding another may be a practical way to increase your input count. Maybe in a future version you'll be able to access multiple DLs from the same instance of Master Fader.
The only thing I'd add is that, as somebody has said recently, a tab based app is better for high input count systems than MF's scroll based system. The Berry X-Mix app is an example, it doesn't look anything like as easy as MF and lacks the 'always there' Master Fader (it's biggest shortcoming IMHO) but, while I can live without the eye-candy, MF is still the nicest app out there.