As others have said, we have so many additional questions for you to help us better answer your question. One thing I wonder about is which way are you leaning - are you feeling very leery of the whole project and looking for advice to walk away? or are you feeling nervous (and maybe a bit excited?) about the idea of taking a new challenge and looking for a bit of encouragement? The answer would greatly affect the advice we will give you one way or another.
I also note your phrasing that you were "asked to make" this quilt, which raises more questions: Who asked? The couple getting married, or one of their family members? How do feel about the couple and/or the person who asked? Are the couple super interested in a DWR quilt, or is that just one quilt design that appeals to them and there are other types that would also make them happy?
I definitely recommend not starting a very large project (and a queen sized quilt counts as large!) with techniques that you do not enjoy. This is your hobby (I assume) that you do for your enjoyment, and you don't want to turn it into a job that onerous and unpleasant. (I think the advice to make a few trial blocks is good if you're feeling like you might be interested in the project.)
I like an old Ann Landers phrase: "No one can take advantage of you without your permission." I find it very helpful when I need/want to say "no" to a request. If this project is not appealing to you, you are well within your rights to say "no". It can be anything from a flat "no" (e.g. I'm too busy with other commitments to take this on), to proposing a different quilt (e.g. I'm not willing to make a DWR quilt, but I can show you several quilt designs that I would be happy to make for you.