i have a Vcore 98d and a Vcore Xi 98. The weight with overgrip and dampener is the same.
The new Vcore Xi 98 feels more solid ,less vibration. in terms of swingweight and power I've didn't noticed a difference between the two .
Yonex VCore 98D / Yonex VCore Xi 98 strung with full poly @ 46 lbs
Pure Drive Roddick GT / Pure Drive Roddick 2012 strung with full poly @ 55 lbs