Just got my rod and reel the guy at the tackle shop recommended 20 lb fc but all i continue to hear is 50lb braid

Its according to the cover you are fishing.  In open water I use 20lb floro, but anytime there is wood or grass around its gonna be 65lb braid.

What was his reasoning for the advantages of fluoro over braid?

 

In this application visibility plays zero part.. 

You're gonna want braid..

It was visibility and that's what he himself uses

If the fish are spooky, Id think the metal wires would pose more of an issue than really thin braid. Thats just me though....

I wouldn't dream of using fluoro with an umbrella rig.  50# original Power Pro works great for me. 

Ya'll are missing out!  I throw the rig quite a bit and for the most part I use 65lb braid, but when the water is dead still and not much cover around I'll switch to a finesse a-rig with 20lb floro.  I get ALOT more bits on this than I do on the braid.  I think with floro, the rigs sneaks up on em and its more of a reaction strike.  Once they see the rig they are more focused on the 5 baits and not the contraption, but thats just my opinion.

I use a finesse rig too, but I still use braid.  No issues getting bit.

I had a lot of bites last year on a rig. I used braid and I don't recall losing any fish. This past weekend I used 20 lb sunline FC and I lost 2 fish back to back. It could have been user error, however my confidence in FC for this technique is done. I am switching back to braid. In my opinion I think you need the lack of stretch to get a great hook set. Confidence is key.

I use the J-Will hooks from Buckeye on my big rigs, and while I don't set the hook hard, just let the fish load up, the stretch in fluoro might be an issue.  Those are ptryy thick hooks on those jigs, even though they are exposed.

What was his reasoning for the advantages of fluoro over braid?

 

In this application visibility plays zero part.. 

for me at least, i use a short length of fluorocarbon with A-rigs for the same reason as i do with spinnerbaits...it's not for the visibility but rather for the stiffness. braid is so supple that it wraps around the wire arms. with 20# FC, it's stiff enough that i avoid that hassle.

for me at least, i use a short length of fluorocarbon with A-rigs for the same reason as i do with spinnerbaits...it's not for the visibility but rather for the stiffness. braid is so supple that it wraps around the wire arms. with 20# FC, it's stiff enough that i avoid that hassle.

true but this is completely different than running straight fluoro on your rig.

Fouling isn't that big an issue.  I think I fouled up three times last weekend, in an 8 hour tournament.  No better or worse than any other bait.