I was under the impression all EA113 turbo engines (and BKD diesel) used the same clutch and flywheel? The whole clutch and gearbox assembly is only rated (by VW) to 280lbft, hence why so many remaps cause slipping.
The VW community has always looked for and preferred uprated OEM solutions over aftermarket for the usual reasons, and nothing exists for the MK5 (that I'm aware of) except the TTRS pressure plate (+ stock friction plate), but I all read about that on the forums is a crazy heavy pedal......which apparently reduces in effort over time, but can you really trust that information to be accurate when there's a £1000+ at stake?
Anyway, I'm on my second Helix. Similar to you, it was only replaced due to a failed flywheel whilst the box was off. Heavier clutches kill DMFs off quicker than a stock clutch does, but then again, so does labouring the engine frequently, so lifespan isn't clear cut.
I'm a picky sod and the fact I've chosen Helix again is a testament to it's daily smoothness and torque capacity. I've done 40-50K miles with the Helix(s), including a lot of bumper-bumper traffic. The pedal is significantly heavier than a brand new stock clutch, but perhaps 30-40% stiffer than a worn/old stock clutch. Providing you don't have chopstick legs and/or dodgy knees, you'll be fine with it
If it wasn't a daily usable clutch I absolutely would not fit it, and just live with the compromises of the OEM parts.
The shunt coming on/off the gas is indeed due to the fooked flywheel. I had the same thing on mine.
The box has to come off regardless mate, so do some careful thinking and man maths. I'd drop the Helix in personally but if you have no intention of tuning the car any further than 250hp, fit a stock clutch. You might get the occasional bit of slippage on a cold frosty morning up a hill in 4th gear. Obviously that will never happen with the Helix as it can handle 400ish lbft I believe.