I curently own a integral designs poncho tarp and use it all the time. I love it however I recently purchased the MLD sil-poncho which I am waiting to arrive. I will continue to be used the ID poncho as a ground sheet for my tent.
The reason I decided on the MLD poncho is there were a couple of features I wanted.
1. Longer tarp, bing 6 foot 1 a slighty longer tarp that I can stake the ends to the ground would be usefull in heavy rains. I take my BMW bivy in string the hood with shock to to head end of my tarp which stops rain from the head end but I always worry about my feet. To be honest however, this has been not much of a problem, but I want to try more camping above treeline.
3. Wider tarp. The extra couple of inches again would provide better protection. It is more narrow at the foot end, but do not need much room there.
2. catanary cut. Being as tall as I am many of the other pitches do not work well, so I am already almosy always pitching an a-frame. Thus the catanary cut is just an advantage for me. Also, it will work better above treeline.
3. Any changes. I do like how my ID poncho is while wearing it. I worry somewhat that the MLD poncho will be too long, if so however, as a custom product, I can have it altered.