HM, IT can be as high as 100%. The percentage displayed is now just the range for the random roll for how much is leeched (times the base leech percentage) with EVERY hit, after factoring in SSI on the weapon and the base weapon speed. It doesn't change the actual intensity, just the displayed value.
Really slow weapons can be at 100% even before reaching 100% intensity in the property.
Of course, it goes the other way as well - compare the current HML & HLL values on the Soul Seeker with that of the actual intensity (which is still the 40% out of 50%, or 80%, for purposes of unraveling).