Just put the dr. pulley 15.5g sliders on my dt300, so im going to share my two cents. English was never easy for me so please bare with me.
In terms of transmission setting I have, everything is stock, no other modification except for this slider, ODO shows 9310 miles.
On my 2013 Jan. model, I got LGE5 version of Variator and Ramp Plate while the drive pulley face plate is LEA7 version.
--- First impression ---
So far, I think 15.5g slider's reaction is similar to stock 15.5g roller in low speeds, however, in higher speed (70mph+) area, it performs as I expected (and better than stock rollers).
--- Comparison, stock ---
With the stock roller, 0-70 mph is easy, but 70-80 needs a little bit more push, not to mention 80+ will need more push to reach.
If I carry another passenger, 80mph is about my top speed.
--- Comparison, Dr. Pulley ---
With 15.5g slider, 0-70 is easy as well, but I have noticed slightly higher rpm compared to the stock roller.
70-80 is easy, and as I wanted, 80+ is a lot easier to reach because the engine revs up easily and smoothly.
Something impressed me is that even with other passenger, the bike gives you a feel like she can handle it without struggling.
--- Personal thoughts ---
I ride on CA autobahn for 60 miles per day, 7 days per week, with many two up riding chances.
It is critical for me be able to obtain enough speed with some reserved speed so I won't get hit from behind by other crazy drivers.
So far I'm happy with the slider. You won't get violent take off power as those lighter sliders may give you, but for freeway cruising, it's perfect.
It is good to cruise at 80 mph because the vibration is a lot less than before, plus, I can easily go up to 95 mph in case I need that power/speed, even with another passenger!
Money well spent!