My conclusion after this years challenge is that Both my G4pm quicksilver and G5 powermac are still great daily drivers for me. I'm not a poweruser and certainly am not an industry guy so my needs don't necessitate cutting edge tech/OS. I can totally understand the folks on here who cannot meet industry/market demands on these old (albeit great) systems. For my ho-hum needs everything worked fine.
Surfing YT - (great on the g5, a whee bit slower on the g4 but still absolutely usable)
Slackchat web client - (Great on the g5, slower on the g4 but still absolutely usable. I did remark on its slowness on the G4 earlier in the week and while it is absolutely slower, I've been using it over the past two days and performance is not a deal breaker.)
MSOffice 08 - (all components worked fine on both machines.)
Websurfing - (worked fine on on both boxes with Webkit/Roccat but was most usable and stable on TFF+BHF+Eric's tweaks.)
Mail - (I used the OSX Mail client on these boxes and they both worked fine. Updating incoming mail was slower at times. Mail always hit my iphone first, then powermacs - often noticeable lag between the two. Moving forward, simply out of convenience & consistency for me, I will continue to access & conduct the majority of my mail using my iphone6s.)
Itunes - (Worked fine on both powermacs. I do not use the cloud for music. I instead have my library saved to a shared external drive. Unfortunately, my itunes wouldn't sync with my iphone6s. To share files, I used drop box which worked really well or would email them to myself.)
Google apps - (I don't use any of them except calendar really. I could log into google+ but it was laggy using all browsers. Once. in, google calendar worked fine for me. I could not connect to google drive though. I did not try the google office suite.)
Garageband, Audacity & reason - (All worked flawlessly on both the G4 and G5. G5 was noticeably faster especially when exporting but I was able to compose, record and create music on both without problem.)
Photoshop CS4 - (Worked fine on my G5. It is a fatboy of an app and doesnt run well at all on my G4. For this box, I have been using Seashore with great success. It's light so its snappy and has all of the basic functionality the non-professional digital arts hobbyist person needs I think to get the job done. I plan to get into CS2 soon for the G4)
Music streaming - (For music streaming, I still use Spotify. It has a good catalogue of my preferred genres: postrock, indie, rock etc. The ads do get annoying however so I rarely listen for too long but hey, it's free lol so it is what it is.)
Foxboxes - ( I have been enjoying FB for some neat added functionality like maps, the leopard store and icloud photo etc. It is slow to start up but once it's up & connected, speed is ok.)
I enjoyed the challenge this year. It certainly helped me to identify problems and fix them with the help/suggestions of folks here. I put these two power macs through their paces.