It's definitely VBL clothing over a base layer for me. I use the silnylon Brawny Gear rain jacket and pants (I bought almost the last that were made).
They double as my rain gear. Rarely does it rain and freeze hard in the same night, so I haven't have to worry about wet rain gear inside my bag. Multipurpose is always good--if it works for you.
If I get too cold in the bag, I can wear my puffy jacket over the VBL layer. This isn't possible with a VBL bag. I certainly wouldn't want to wear down inside a VBL! If it warms up during the night, I have been known to remove the rain jacket and pants. I keep them handy, though, because that usually means it will be raining by morning.
This practice won't work with breathable rain gear, though. My own finding is that I get as wet inside breathable rain gear as non-breathable in warmer weather, so if it's raining and relatively warm, I just get wet. Thanks to modern fast-drying fabrics, my clothes are dry 15 minutes after it stops raining, as long as I am moving. (That was also true the time I fell in the creek!) If it's cold, I have no problem with the non-breathable rain gear.
Everyone seems to have a different reaction to vapor barriers. For some, they become a sauna even down in the teens (F). For me, in my sleeping bag, the VBL suit works fine below 28-30*F and definitely keeps my sleeping bag drier.
In other words, YMMV! You need to find out what works best for you!