People are tripping about how efficient the Lotus is, a newer lighter based vape. Someone was claiming it's just as efficient or more by virtue that it can be taken to higher temps than a PD.
If you already have a 18.8 bong you could get a glass vapobowl shipped to the US for a paltry 28 dollars or so, or a vaporstar if you don't have 18.8. Vapocane B (untested by forum, mine's in transit now) can be had on EDIT for like 40 bucks.
Make sure you check out the retailer discussion thread for coupon codes before you buy anything.
I love my MFLB for being truly the most stealth vape there is, short of some of the Vapir portables which taste like burning plastic. While I am very glad the MFLB is not my only vape, it is also a wonderfully potent little package and does stretch your supply. Just today I roped it walking up the hall in a hospital on the way to my appointment, no one knew.
I think the MFLB+(bong N Vapobowl) make for an excellent, versatile way to have all-terrain, all-circumstance vaping for about 120 bucks.
On the issue of the DBV and SSV, I'm sad to say I've tried neither. I know that the DBV has a heater angle similar to inexpensive box vapes, which is a horrible idea and causes material to fall out of place. The SSV has a far better design to its heating element's placement (or would seem to imo) and would probably be worth the extra expense for that alone. Keep in mind that the Extreme Q, Zephyr Ion and Herbalaire can all direct draw and bong while ALSO being able to fill bags. A little extra expense may be well spent.