Casting distance???

I have 2 shimano rb 6000 st baitrunners that i use on my barbel rods for carp fishing they are 2lb wychwood rogues .
My question is if i got 2 shimano st 4000 fd reels will i loose much distance on the cast? As the 6000 seem a bit bulky with the 2 handles.i like a single handle im currentlt casting a 2oz lead plus my bait and pva stick 65 yards any help much appreciated.

I have Said before on the forum that I used to beach fish and could hit over a 100 yards … it all down to the way you cast and the rod and reel you are using … you can have 3 different make of rod all with the same spec not one of them will cast or handle the same … the same can be Said for reels. Some set up can be un-balanced top or bottom heavy. A well balanced rod will cast a 1oz as far as 2oz. You don't need heavy weight to get distance … (heavy weight are not needed on still water)

I have a 10ft feeder & 2500 DL reel casting 15g method feeder and can get 30 - 40 yards

Whilst beach casting yesterday I am sure that on one cast my lead and bait entered Algerian territorial waters! I didn't get it back at any rate

As Chris said above, casting is down to technique. I've fished loads of matches on ressies and big pits and been out-cast by other anglers. The crow also mentioned his sons ability to cast further than himself using the same rod and reel.
One thing I have noticed is, anglers who can cast very long distances seem to make it look effortless. Using a clock face as an example they swing the rod back to 2oclock and release the line at 11 o'clock. A very short sweep compared to beach casting style swinging the rod back to 3 o'clock.
Being right handed I hold the rod at the reel seat with myright hand and left hand at the base of the butt, my casting has improved a little since I started putting more effort into pulling the butt back with my left hand and putting less effort in with my right hand. There's a definite sweet spot as the rod flexes which you can feel as the line bites into the finger you are holding the line with by the spool on your reel, releasing the line at this precise moment plays a big part.
Sometimes your rig will go high up in the air while other times it will go low and land close in with a big splash, ideally you want it to travel straight out.
As with most angling methods PRACTICE is often the key to success...

I once watched an ex competition caster fishing from a beach once, where his lead landed I have no idea but it took quite a while to get there, your right Simon he made it look easy and that was using leads no bigger than a carp angler might use.

You will be able to cast 65 yards with 4000 reels no problem.