Try it and decide for yourself. I like it and I like camping also.
Insects are not a problem, it can be missable but it can also be great. When you're in a tent you are safe from rain and elements but also a little more dettached.
When you're in a Bivi you fall asleep while looking at the stars, wake up a few times in the night see how the stars have moved and generally wake up and watch the sun rise which is great also. This is something that is brilliant and should be done.
If it rains and it's coudy and you're out for a few days then a tent makes more sense.
With the weather as it is today you don't need a tarp so yes, lighter than camping unless you want to buy a Terra Nova.
Like I say try it, worst thing to do would be to not try it. You may hate it you may love it.