For the curious, I did a whole bunch of math about level 11 vs level 12 collectors, before and after the boost period, and how it affects your time to paid off amounts and such. Let's dig right in, shall we? First, let's define our variables:
Level 11 Collector/Mine Hourly Production: 3,000
Level 12 Collector/Mine Hourly Production: 3,500
Real Cost To Upgrade: 696,000 (336,000+5 days of lost production / difference in production rate)
Elixer Boost Period: 16 days
Gold + DE Boost Period: 8 days
level 11 Elixer Collector Boosted for 16 days, production: 2,304,000
level 12 Elixer Collector Boosted for 16 days, production: 2,688,000
Difference: 384,000
level 11 Gold Mine Boosted for 8 days, production: 1,152,000
level 12 Gold Mine Boosted for 8 days, production: 1,344,000
Difference: 192,000
Time to pay off level 11->12 upgrade, from the moment you press upgrade: 63 days
If you finished upgrade before boost event,
Time to pay off elixer collector upgrade: 47 days
Time to pay off gold mine upgrade: 55 days
Which also makes sense, if you think about it. If you have 16 days of boosted elixer collection, that should cut off the time to pay off by 16 days (63-16 = 47). Same for the 8 days of boosted gold mining.
Few more numbers to put the total amounts gained from all 6 collectors/mines:
6x lv11 Elixer Collectors for 16 days of boost: 13,824,000
6x lv12 Elixer Collectors for 16 days of boost: 16,128,000
Difference: 2,304,000
6x lv11 Gold Mines for 8 days of boost: 6,912,000
6x lv12 Gold Mines for 8 days of boost: 8,064,000
Difference: 1,152,000
So, the difference is not actually all that much. A total of ~3.45 million resources (~16.7% more) difference if you managed to get your collectors/mines upgraded before the boost events happened.
However, if didn't have level 11 collectors/pumps, here's how your production would have stood up:
Level 6: 8,985,600 (baseline)
Level 7: 11,059,200 (+123%)
Level 8: 13,132,800 (+146% over baseline, +118% from previous)
Level 9: 15,206,400 (+169% over baseline, +116% from previous)
Level 10: 17,280,000 (+192% over baseline, +113% from previous) - Max for TH5
Level 11: 20,736,000 (+230% over baseline, +120% from previous) - Max for TH7
Level 12: 24,192,000 (+269% over baseline, +116% from previous) - Max for TH8
That's for the total resources generated from just the boosted portion of your collectors (16 days)/mines (8 days). Personally, this confirms for me that level 12 collectors for TH8 is perfectly in line with all other collector/mine levels, and leaves room for a level 13 collector/mine option for TH9, and a level 14 collector/mine option for TH10, without going crazy.
Then, just for fun, I calculated the amount of DE everyone from TH7 to TH9 got from boosting their DE drills. I assumed max level for everyone (1 lv3 drill for TH7, 2 lv3 drills for TH8, 2 lv6 drills for TH9). If you don't have max'd drills, you can see what you would have produced, and then use one of the lower TH's production levels to see what you actually produced.
TH7: 17,280 (enough to get BK+~half level 2 upgrade)
TH8: 34,560 (enough for BK 5->6, and half of 6->7)
TH9: 76,800 (enough for BK 10->11, with enough extra for any single AQ upgrade up to level 4->5)



It would just give those of us in TH9/10 a little more of an experience like what th7 was like, with bigger targets available.

