Okay, so I've been sitting on this (e.g. I was lazy) but now is as good a time as any to post, I guess. So to anyone keeping score, I am now on my 4th Solo unit. My first one lasted the longest at 4 months. Sadly the electronics took a shit on that unit. Sent it back to PIU, and got one of the "new" models. Increased airflow, fast heat up time, ability to charge/use, stainless steel colored bowl... It worked awesomely. Until I noticed a restriction in airflow along with a corresponding decrease in vapor. This got worse over the course of a few days, so I emailed Randy over at Puffitup, and he agreed to RMA it and send me a new one. A few days later I get my replacement, replacement Solo. Still new model, same as before. Worked so well out of the box it made feel stupid for ever doubting that my other replacement was decreasing in performance! Super free draw and super fast heatup times. Also made some amazing clouds! Sadly, this also suffered the same restricted draw/decreasing vapor as my previous one. Contacted Randy at PIU again. He suggested I clean the bowl with iso and poke out the air holes. That didnt work so he agreed to send me another unit YET AGAIN. So now I have Solo #4. M1A4 model for anyone who cares. Stainless steel bowl like the other two, charges while in use... but the draw is exactly like my very first Solo. More restriction than the other two replacements for sure, but nothing id consider "bad". Also takes longer to heat up. Thing also produces some massive clouds, just like Solo #1 (slightly less so than Solo 2 and 3). So... yea. You got me on this one. Ill allow you guys to draw your own conclusions here. I just hope this Solo stays in proper working order for years to come. Oh and this is also a testament to @PuffItUp and their awesome customer service and Solo return policy. I would have told myself to fuck off after the 3rd time, lol. Did I mention they PAID FOR SHIPPING BOTH WAYS EVERY TIME? Well they did.