As long as you keep your original files intact, it won't hurt to send them a jpg.
Just make sure you save it as a High Quality jpg (low compression).
The problem with jpgs occur when people only use the jpg format for editing and saving.
They think that jpg is great because it saves such small files. But the small file size comes with a price to pay - reduced image quality
Every time you save a jpg it throws away some data because that is the way jpg can create small files.
As long as you only save a jpg (high quality) to send to print and always go back to your original tifs for editing you should be ok.