Blu has been reported to be inconsistant.
Many who originally purchased a Blu ended up spending money to 
buy something else later.  I had one given to me for a little while and I gave it back.  Terrible little thing.  Hardly any vapor.  PIA to refill the cartridges.
If you like the look of a Blu and the size, a 510 with a PCC charger should fit your needs. The atomizers put out a ton of vapor and my 510 atomizers have lasted for over 6 months (I've never had one completely die and only one is too funky to bother with).
Only purchase Joye brand 510, as they are completely reliable.  Get a bottle of liquid for what ever model you 
buy.  You'll need it right away even if it has prefilled cartridges (which don't last very long).