Pros: Better price so far, equivelant light, plants love it.
Cons: Some RFI on channel 2, but that'll go when we're digital.
The output is pure white, there's no buzz, and my plants can't tell the difference. That being said, you do have to bypass the ballast in your fixture. A little easier with the newer shop lights, as they're totally electronic. Still, you'll want to either have an electrician friend to do it or proceed with 110V AC caution. Once done, you'll have the "hot" on one side of the light and the "neutral on the other side.
The downsides are few - actually two that I know of:
1) Cost - approximately a 4+yr return on investment: they're still $65US plus shipping (they packed them well, and despite falling over once outside the fixture, they're working fine, and
2) Some RFI (Radio Frequency Interference) showing up on channel 2 on our TV - of course that should disappear after we go digital. I've got an email into the engineers about, and will update once we've found a solution.
Overall, they're great bulbs and I'm thankful that some of the stimulus package went to these. If I can replace the other three sets of bulbs, I'll be saving 34 Watts per set, and hopefully offsetting the cost with more gardening starts as well.