I can only compare it to the 6.1 95's. I don't have experience with the Pure Drive.
I strung the 98's 2lbs higher with the same string combo, and the stringbed feels more bouncy. It swings faster and generates the same amount of spin. However, this spin comes with increased power. This has a big implication: with the 98, there is less ability to increase net clearance. No loopy shots. Aim 1 ft above the net. If you aim 1.5 ft, you start hitting a few long.
My playing style changed to 3/4 swings, guiding the ball. Full RHS is either a winner or a UE.
Kick serves jump forward with the 98. It jumps high with the 6.1.
Less stable in off-centered shots.
No arm problems with the 98, partly because the stringbed is so cushioned. You can feel the ball sit on the strings longer.
Anything else you wanna know?