Hi Gordon;
My shop is basement based at the moment. When i moved the basement had two 60 watt bulbs on each side. As you can imagine pretty worthless for old eyes.
Over the years i replaced those with various 4 foot fixtures. Frankly in placed i had to do this twice as i underestimated the light required for some work.
About three tears ago i started to replace failed fixtures with LED tubes. This is relatively easy on a 4' fixture. I used the LED tubes that require ballast removal. As noted above the other type only work with certain ballasts. In my case with many fixtures purchased over time, it wasn't worth figuring out which ballast would work.
So if you go with what is called a ballast bypass LED bulb you will find yourself having to remove the old ballast and wire the fixture as the instructions say. This is not a big deal if you are somewhat familiar with electrical wiring. It might be 5-10 minutes per fixture. Then you just plug the bulb in, power up and you have bright lite.
Now about those bulbs. First the come in various color temperatures actually i believe there are three different color temperatures. I chose day light.
In any event these bulbs are very bright. In many locations i replaced two fluorescent bulbs with one. Each fixture though is wired to support two bulbs. Im very pleased with the light output.
I would take the time to figure out if current lighting is good enough. If you are working on the light it is a good time to correct any dark spots in the shop. This especially over a work bench or stationary tool.
Now all of that being said id be careful to look at the condition of your fixtures because the reality is some fixture can be had pretty cheap if you catch a sale. Ive replaced a few ceiling fixtures in the house with new LED fixtures and have gotten excellent results from round and square units. Im pretty sure such fixture would work well in a shop. You can also find unitized 4 ft LED fixtures on sale at competitive prices.
I suspect that some of these discounted fixture are the result of discontinued items.
I guess the point I'm trying to make is that LED bulb replacement makes sense in most cases. However if you need to change the lighting layout or have really old fixtures you might want to consider alternative fixtures. Either way you wont be disappointed.
It looks like I can purchase a retrofit kit for the 8 foot fixtures to replace the two 8 foot bulbs with four 4 foot bulbs. Amazon has the kit for about $9+$5 shipping. Some of the bulbs state that you do not need a ballast and others seem to indicate that a ballast is required. Kind of confusing. I will talk to my electrician friend on Saturday.