1)Nowhere did I suggest the 2700X's stock cooler needed replacing for overclocking. I AM taking into account however, that not everyone is comfortable with the AMD stock coolers; the blasted things can get loud. YOU seem to be fine with it though.
The OP is an unknown though. I figure it's better to play it safe.
2)Who actually gives a banana about BASE clocks? Next to no one, because the darn cpus don't run at those speeds anyway unless the user is doing something wrong.
Also, yeah, just go ahead and disregard Ryzen 3000's higher IPC that allowed it to rival Intel in gaming and completely stomp them in productivity.
3)Ryzen 3000 is an entirely different player in the overclocking field. Just overclock the memory, tighten the timings, and keep it cool.
Setting a static frequency hurts performance.
Overclocking the core frequency can be pretty bad, as people have actually managed to quickly degrade their chips already:
View: https://www.reddit.com/r/Amd/comments/ejgc6p/1325v_is_not_safe_for_zen_2/
Pushing past your chips maximum FIT voltage is not safe and will cause accelerated degradation.
Obviously, each chip is different. So you have to find your personal chip's safe FIT.
Also, do not push past the Fmax on your cpu while at maximum FIT voltage.
Fmax is set by the cpu PB and increased by PBO. So if you are at FIT or above, have high temps and are higher than FMax. Then your cpu could degrade.
2700X overclocking: Help yourself, I guess. It's got more headroom than a 3600 for it... doesn't impact the pros and cons in any meaningful way though.
4)The problem with motherboard VRMs is the cooling, or complete lack thereof, and not the power phases.
Blame the manufacturers for that one.
5)The TDP rating means jack all. Look for actual power consumption numbers.
6)Your summary-
1st line: Bang for buck - nope. The odds seem to favor the 3600 more.
The 2nd line... WTH, I'm just going to skip that.
3rd line: I think you meant the 2700X and not your 1700. Anyways...
'Future proof multi-threading'...
🙄 then watch as the 2700X and 3600 become obsolete in the next 5 or 6 years anyway, IF no one bails out like AMD did previously.
The only reason Intel's older cpus aged as well as they did is because of no competition for almost 10 years.
New tech comes out literally every year. 'Future proofing' is an exercise in futility.