Changed out a bunch of four foot flourescents to the led type that requires no ballast. The ballast is internal in the bulb so all you have to do is wire it straight to the 120-277 volt coming into the fixture. Any downfalls to these other than the price I'm not aware of yet. One manufacter is 10 year warranty.
I can not specifically say what's good or bad but there's good and garbage out there. I'm trying to put something together here and out it on the forum to help sort through the mired of the good versus the bad. Don't buy in to the sales pitch or the pretty packaging. At least go with a reputable manufacturer. What good is a 10 year bulb if everything goes gray under the light after 5000 hours. The manufacturer of this 10 year bulb, will they be around the next 10 years to pay a claim?
I have great resource that will help us all to muck through. DOE has a great data base where manufacturer can register their wares and must meet certain criterias. Go to www.lightingfacts.com and poke around. It's a little clunky and the search engine is temperamental. Just because the an LED light or bulb is not listed does not mean it is a bad bulb. It does mean you have your homework cut out for you.
I've attended a conference on LED a couple years ago and there is a lot of great things coming. I highly recommend to start agressively educating yourselves on LED lighting and even lighting design. The rules of thumb for lighting design do not apply to LED. They don't even apply from one LED another. Fundamental lighting design is crucial to LED lighting.
I know utilities are using them for substation control house lighting, and even the indicating lights on control racks are being changed to LED. Also, it seems a minor thing, but it wasn't that long ago when we had to carry those big clunky spotlights into poorly lit spaces. Now I carry an LED spotlight that fits in my pocket. Think of all the advances in lighting design over the last decade, it's almost impossible to keep up.
I've seen quite a few LED tubes in commercial installations here so someone must believe in the viability. A "downside" I can see in retrofit situations is if a non-technical user attempts subsequent maintenance using a conventional tube. Stupid? Yes, but I've met a lot of people who think that if any lamp physically fits it must be OK. I do believe that retro-fits should be clearly labelled, "Caution LED tubes only". Since moving house 18 months ago I have equipped with almost entirely LED lamps in a range of styles, though not tubes. The biggest difficulty I found was judging the wattage needed for subjective comfort levels. I guess this was done from experience with incandescents, so will come with experience. Afterthought: With an estimated 40+ lamps I've only had one premature failure, and that was very early.
What would happen if someone did replace an LED tube with a regular fluorescent? I recently discussed that with some Germans and our verdict was it simply wouldn't work but without any dangerous consequences. Without a ballast the tube should simply be an open circuit since the supply voltage isn't high enough to start the lamp.
"What would happen?" On a good day, nothing as you say. However, it takes little to strike a tube. In dry conditions the static generated by lightly brushing the tube can do it. You can start a fitting with failed starter that way. Also a transient on the supply could easily exceed strike voltage. If a tube strikes with no ballast it is virtually a short so the breaker trips. I imagine the glass could shatter though I've never seen that. The energy dispersed will be a function of the breaker characteristics.
The key with LED is do your homework. LED' inherently put our a high, UV and low red spectrum. You can have a LED bulb with a CRI 80 but anything red under it is gray or black. The LED's can be doped to fix that however that coating will be bombard by the UV so then it will come done to the quality of the doping. Rules of thumb for lighting do not apply to LED lighting. Rules of thumb from one LED light does not necessary apply to another LED.
Retrofitting of existing lights can be trickier. LED' can operate at varying temperatures however They are not tested in every type of light fixture out there so they are listed as "Classified", not "listed". It means it's listed per say providing you install and use it within the designed parameters however they do not know how it will work in your setup and if it fails, it's on you, not them, thank you for your business...
Do the research, use reputable brands, don't buy the sales pitch, don't buy the box, buy what's inside the box. When retro fitting, do a few and wait. SE how they perform. When buying LED's for a larger area. Buy at least enough to finish an entire area or room, don't stop in the middles. Get educated on LED and lighting design.