Musical Surroundings Phonomena II+ -OR- Moon 110lp v2 -OR- Parasound ZPhono XRM Phono

With your existing table and those price points, I'd go for the something in the middle.

Choice of phono cartridge will make more a sonic difference.

"nearly twice as good" 

Not the expectation to have with audiophoolery.

Maybe look at the MS as being more competent with the next table upgrade.

At that point you're looking at something $2-3K+

"My current phono stage is in my Musical Fidelity A3.2"

The phono stage in your amp will be "bettered" with a stand alone unit.

How much will only be found out by hearing all 3 at once in your setup. 

With your existing table, I wouldn't go beyond the Moon, based on it's age. The latter Rega designs are improved and noticeably "better".

If it were me, I go with the Parasound, since It essentially will do everything the MS will. Get a $500 new flavor cart at some point and be done with it.

Any curiosity after that is a step up to a new table and next level phonostage-more wallet opening.

By then, you'll want an amp and new speakers too.

" It's one year old."

Oops! I owned a P5 when that series was relavent. When I see "P3" I think the series from the 90's early 2000's.

The Rega line is great for what it is. I guess it's a sign I'm showing signs getting on in age.