I like using both. Gives you loads of options. Having a light bivy makes sleeping without the tarp easier, having the tarp provides you the chance to get some living space that is sheltered and using both together lets you ride out some harsher weather.
>>2052405Poncho tarps are cool, pretty niche as they are small. So you've either got to expect very little bad weather or be cool with hanging out in a coffin while you ride out a storm. I haven't used one but my smallest tarp is about the same size as a poncho tarp when pitched. In a low A frame, the best pitch for a tarp this size in bad weather, you've basically got to lie on your back and not move very much. It's real test of your sense of humour.
