The DNA will be the least regulated power hungry board currently out due to its HIGH 97% power efficiency, buck-only does wonders for a board. The boost/buck system plus Yihi's typical efficiency numbers will leave the Q at 76-81%ish in my opinion if not worse. Plus the VS DNA200 has 2 amp charging.
Not to mention lithium polymer batteries are far superior to lithium ion 18650's. Yeah I'm biased, I'm an electrical engineer who works for a lithium polymer battery company, doesn't mean it isn't true. The SX450J board on its own may be great if we ever even see it, but given it's a Boost/Buck chip will always leave it behind in the efficiency bracket compared to a buck-only system. Li-Po batteries sag far less internally on average due to better battery chemistry because there's more to work with when designing a Li-Po cell, designing an 18650 is a multi million dollar process and it becomes difficult to improve them marginally because you're limited to an 18650 sized tube. Li-Po packs can be virtually any size and have a superior chemistry.
Batteries aside, pulling both a SAFE and LEGIT 200W out of two 18650's after battery sag and ESPECIALLY at lower battery voltage charges (god forbid this be a high wattage pull while the board is boosting the voltage, the input current will be through the roof and you'll be risking thermal runaway but I'm sure the board won't allow this in most instances) because even the best 18650's only have a CDR of around 25-30A when took to bench tests. Plus due to their higher internal resistance and limited chemistry, they sag far harder ESPECIALLY at higher power loads.
Software. SX-Q hurts my eyes and Escribe has FAR more options in terms of what you can do with the mod. For example, last time I had my ML on the software, I saw NO options for mod internal resistance and case thermals like Escribe has. This can play a huge role in accurate power delivery to the atomizer. Then the DNA has up to 8 profiles and it's just easier in my experience to work with a DNA and get accurate results in TC than it ever was with my let down that was the ML Class 350J-V2. If you go to a Renegade style high-wattage 350J-V2 things get better, but, not DNA better.
All in all, the DNA board just does more than the 450J, the Escribe software has more than the SX-Q software and the board itself is accessible while with this FDA thing and Yihi's lack of a response to the topic, we may NEVER see a modder 450J board on the market.
At the end of the day, if you want more functionality, more efficiency, a real 200W, more options, etc. the DNA200 seems like the board to go with. Plus with a DNA you currently have a ton of retail mods to choose from and DIY options. The 450J is limited to the Q Class, at least right now.
Unless you're just a fan of Yihi or in my case are curious and have money to blow on vapeocalypse spare mods for the FDA Doomsday survival, I see no reason to pick the Q-Class over a DNA200 powered device right now. Sorry SX, ever since the DNA200 was released you just haven't been what you used to be. Back in the DNA40 days I would've picked SX every time, now I see myself never picking SX other than just to try out the mod.
The only thing I even SAW on the prototype model (this wasn't too long ago, it was a late-stage prototype so don't go raving about how so much can change, the reps themselves said it was going to be VERY similar to the retail launch Q Class mod) that made the board different than the 350J-V2 was this SX-Pure technology bullshit they employed with the IPV5 SX330WePimpedThisBoardOutAgainBitches powered mod. The SX-Pure technology was a load of garbage and lies on the IPV5, even when used with their Altus ripoff RTA that wasn't any better than the failure that was the Altus. So, like I said, I'm not holding my breath. Mine will be here sometime this morning, so, I'll let you guys know how she does but I HIGHLY doubt it's going to win my affection over the DNA200.
Yihi seems to just be slapping pointless features and wattage increases on the SAME boards and releasing them as something new lately. They re-purpose boards like motherfuckers, I do not honestly feel that they're focused on developing new technology, instead they're focused on re-purposing the same shit OVER and OVER again until there's just nothing left to slap onto the same board. The SX330 has been re-purposed god knows how many times at this point, the 350J-V2 has been updated too many times to count firmware-wise and I don't see the 450J being any different. Evolv has Yihi throwing shit to the wall just praying something sticks. The IPV4 and IPV5 weren't Yihi devices, but they used Yihi chips, the SX330 has been pimped and souped and soldered to hell at this point and the mods housing them have all been crap lately.
I'm sure the SX-Mini Q Class will be a great mod, I'm not doubting that. Just no greater than a Renegade SX-350J-V2, and definitely not better than a DNA200 device.