Maths methods definitely helps out further...If you're willing to do the work. There were three of us in my class this year that did methods and further. Me and my friend have aced each further sac. I'm ok in methods but I'm really good in further, because things just click a bit easier. But the other kid who does methods has almost failed twice.
But don't think that because you're doing an "easy" math that gives you the oppurtunity to slack off it. I worked hard on both maths, and I finished all the work two terms before my class in further and it was I believe because of this that allowed me to a little less stressed before exam period.
If you are thinking of doing further along with methods, be warned the first part of further (core) is boring as hell...and you will be inclined to muck around in class. Don't! try and finish as much of the syllabus initially as you can, it will pay off very much later in the year.
I just sat the further exam, and I was ok I think I scored probably 35/40. So not too bad, but I did prep fairly will and studied both for further and methods.
Good luck, hope i helped!