Hello. I am (very enthusiastically), awaiting arrival of my P5 with Groovetracer subplatter and Exact 2 cart. I'm currently using the same phonostage as you, a Graham Slee Era Gold Mk V with a Music Hall 2.2 LE table. I assume you have no intention of replacing the Graham. I think it's amazing, even with the budget Music Hall. I'm sure it sounds great with the P5....as I will soon find out.
I will also soon find out how the P5 sounds with the new phonostage I have coming, a Clones Audio PA1. I had no desire to change phonostages, but after owning the Clones 25i integrated for the past three months, I HAD to check out Funjoe's new phonostage. His $890 integrated sounds better to me than $9,900 worth of seperates I used to own.
I bought the Music Hall a month ago and it's my first attempt at vinyl....so far I'm LOVING it.
So, in the next few weeks I'll A-B the Graham with the Clones. I have a strong feeling the Clones will come out on top. Just letting you know in case you were interested.