I applaud recycling and re-using.
However, the idea of recycling a 5p transistor which may, or may not, be damaged or partially damaged by maybe overheating it while tying to remove it from a PCB which may or may not have been working due to (sod's law) the transistor I have spent three hours removing is, in my very humble and inexperienced opinion, a waste of time - unless desparate of course.
I also use your 'hoarding' policy and have ended up with piles of stuff.
In fact I have more piles than a Hospital Haemorrhoid ward.
I think you were very wise to abandon the hacking.
It is not absolutely straight forward to design your own pcb around energy metering chips.
Yes, the Data Sheet pinouts look oh-so-easy don't they, but it requires very careful design of the power supply, careful input filtering, careful PCB design so it doesn't blow up and careful calibration. PCB design is crucial, as accuracy and stability are hugely important and you may be mixing big and little voltages as well as analogue and digital cicuitry.
It is well beyond a 30 minute thrash with Eagle after getting it for Christmas.
My (limited) experience of the cheapie plug-ins has had mixed results.
I have one plugged into a PC + monitor right now. It claims to do all the PF stuff but says my 19" old CRT monitor is using 1 watt.
On the other hand it said my 25watt Weller soldering iron was using 24.5 watts. So a mixed bag of results.
But if you can't trust it then what's the point?
(I always think that 'trust' applies to
all instrumentation, which is why I don't buy cheap 5 quid 'scopes and multimeters for pukka work.)
Unless you have 500 years experience, a shed-load of proper test-gear, a pile of knowledge and skill, I would, with the greatest Festive respect, suggest leaving energy metering stuff to the Big Boys who know what they're doing, or very experienced amateurs (who think they know what they're doing
- especially those with 5 quid Ebay 'scopes)