For me the only downside to HPA is the issue of where to put the tank- praise be my luck in finding a teeny lil unicorn tank to put in the stock

I would personally consider an HPA rifle built by myself to be more reliable than spring; it's just the system I'm comfortable with- I can see why people would say spring over HPA there.
I will note, my intuition says springers should actually be easier to get to "perfect" consistency than HPA (note: your chrono isn't accurate enough to ever read perfectly consistent shots, so as long as you're within ~3 FPS, you have essentially perfect consistency), though I'm unsure of this- and spring may also be the cheaper route. However it gets complicated. Maybe it's true my build took more money to get to than an equivalent springer build, but mine can adjust power with the turn of a screw, meaning very convenient and no need to buy multiple springs...BUT getting even MORE complicated, this alters my output volume and some spring platforms actually support very quick spring changes, in which case altering the power while keeping volume static is much easier for the springer than for me, disassembling my Wolverine Bolt to adjust the tune.
In the end, my perspective is this:
Lack of bolt pull resistance is quite significant to me for concealment and the occasional quick follow-up shot (also just one of those things- I can't go to the other side after having gotten comfortable here), suppressing the system is much easier and gives me options (
the quietest airsoft gun on the planet via solenoid valve versus
slightly shorter barrel with a more intimidating muzzle sound), instant power adjustment so I can always be right at the field limit (different for the 4-5 fields near me- all measure in joules so no wiggle room via chrono-ing on irrelevant weights), and the cost difference is questionable enough that I'm not even 100% certain it's worse. The only question I ever had in my mind was where I would put the tank, because I did not want it attached to me- a little bit of luck, creativity, and hard work resolved that.
Btw OP, the forum doesn't take kindly to embedded YouTube videos- here's the link for those curious, or who didn't know he even posted a video:
youtube.com
/watch?v=opOmYw2B7y8
EDIT: Forgot to mention one other downside specific to the Bolt- the battery. Unlike what seems to be the majority argument, I don't believe the need for charging is relevant - it's simply far too infrequent (a tiny battery lasts months on end) - rather, I am paranoid and would prefer not to have any electronics present at all. That being said, I don't regret buying the Bolt because it's the quietest system possible. I hope to build another rifle with the Bolt M or SDIK to play with pressure curve, at which point I'll keep the Bolt classic around inside what I'll ensure is the utmost silent rifle on the planet. One day...