Eric,
I just made the switch over to a bivy and tarp this year.
I have the MLD Soul Side Zip Bivy and the MLD Poncho/tarp.
Love my bivy and really like the convenience of having the side zip for ease of entry and exit and think that the extra ounce is well worth it. (When I wake up in the middle of the night and need to go pee on a squire, I want out fast!).
My friend has the same poncho/tarp, but uses the Super Light.
It really has many of the same critical features of the Soul Side Zip and is lighter and cost less than the Soul Bivy, making it worthy of your consideration.
Since my poncho tarp is my shelter and rain gear, I do take it all of the time.
Yes, the poncho tarp is a small tarp, but sleeping in the confines of a bivy, it seems plenty of room to keep my gear dry.
One thing I can say is that Ron makes really great stuff that shows a clear attention to detail.
One of the pleasant benefits of moving to a bivy is that I have been able to go to a lighter sleeping bag because of the extra warmth that the bivy provides to my sleeping system.
Hope that this helps.
-Tony