The pre 2004 bikes only have 1 connector like the pic near the regulator the later bikes have 2. It melts very rarely on the earlier model but it has been known.
The 500w stator is the main reason for the problem though. The way the rsv charging system works is to produce 100% stator capacity 100% of the time and dump the excess via the rectifier hence why the heatsink is always very hot.
That means those connectors have all that juice constantly running through them and the moment they develop the slightest resistance through dirt etc then they heat up much like the rectifier and melt.
on a 370w stator you are pumping out less juice so things don't get so hot, hence less problems.
As it happens Aprilia are now producing a 370w stator for the post 04 bikes but they have not made it known generally. It kind of sneaked onto the parts list.
Without going into detail the reason is suspect the pre 04 370w stator won't last in the later bikes is thus.
There are 2 ways to alter stator output. firstly the number of windings on the stator. second the magnetism of the flywheel.
Aprilia (denso) went the magnetism route but also had to alter the winding design to cope with the heat of the extra output.
If you put a pre 2004 stator in then you are putting the winding designed for a much lower magnetism flywheel into a higher temp situation than it was designed for and it's gonna get hot. How long it would last :dunno maybe depend on the sort of ride lengths you do etc.
