These bulbs are accurate in terms of temperature. he most important thing when it comes to bulbs is that they emit the proper temperature. I have experienced bulbs emitting the wrong temperature but not these. Using these wuth a Lowel Omni they emitted correct light K/temp for softboxes and as a small flood/ key light. As with all Tungsten, They get very hot--make sure if you pair this with the correct temperature softboxes if that is your intended use.
I assume they will have a full life but I haven't used them that long so I won't give it a full five start because I don't know yet, not because I have any issue with them . theyare great and I highly recommend them.