As with all things there are trade-offs for going "lite." I'm an audio editor (Pro Tools) so don't use NLEs, but I interface with editors all the time. FCE does not export OMF, which almost every sound editor will need, so if you are going to work with a sound editor you will have another possibly costly step. If you are going to DIY the audio FCE audio implementation is very minimal. The same is true for FCP, but FCP comes with STP (Sound Track Pro) which, although not great, is a vast step up from what FCP or FCE offers. I'm sure that others will chime in on functionalities, plug-ins and workflow with regards to FCE vs. FCP.