I now alternate between a Bivi and my tent. My Bivi is great for short trips, (usually 1 to 3 nights, max 7) especially when I want to wild camp near to villages, less distance to walk from the pub after dark. I started by taking my 3.5 Alpkit tarp with me as well, but I now just take my umbrella. I've been lucky to date, its rained, but not when I got in to it, or got out of it, just in between. I know that one day my luck is going to run out, that will be a real test!
For longer trips I use my tent, which I will do in April when I attend the Borrowdale meet. I've made my mind up that from 14th April I will go from Borrowdale to Carlyle on the Cumbria Way, along Hadrian's Wall to the Pennine Way and then hike north to Kirk Yetholm. From there I will hike to Edinburgh. About 12 days I think, wouldn't want to Bivi for that long!