I have a Mac Cat Deluxe I used to use with my HH EUL. It always kept me dry but I was paranoid that I would get wet in a real good storm.
Since switching to the JRB BMB I have only used the JRB tarp. No worries about getting wet under that thing at all! I've experienced some of the hardest rain I have ever camped in and not only stayed dry but was able sleep sound without checking the tarp every so often.
Once I get chance I will try setting it up with the Mac Cat and see how it looks.