Hi tuttle. Welcome to FC. First, let me get you straight on abbreviations. It's DBV (Da Buddha Vaporizer), not BDV, and we don't add the 'V' to PD. It's just PD for 'Purple-Days'. "the bay" is eBay (not really an abbreviation there though :/ ).
No, you do not need two vapes to fit your needs. You certainly can vape a small amount in the 7th Floor units, or any other vape for that matter. It's just that the PD, with its tiny bowl, makes it easier to vape small amounts. It's like eating a frozen dinner. When you take it out of the box and look at it, it may not look like it's enough food to fill you up. But a few minutes after eating it, you may well find that you're no longer hungry. If you'd eaten out at a restaurant, or your wife cooked a big meal with plenty left for 2nds and 3rds, you'd probably end up overeating. That's the tendency with standard sized whip vapes. You end up taking big hits and finishing off the bowl, and then you're ripped when you really only wanted a small buzz. But the way around that is to just load a small pinch in the big hitter, or load a big bowl but only take a small hit (the latter option is much tougher
). You can get small hits and efficiency from big hitters, it just takes some discipline and it's generally not as enjoyable as doing the same small amount in the PD.