|I have never had weather helm on an RL28 to the extent you mention. Certainly there can be a heavy pull needed on the tiller when reaching in strong winds especially under spinnaker, that can be fixed by easing or reefing the main - but it feels slower and is not as much fun. |
It is worth reading Steve Leicester's and Phil Moffatt's comments under "Reefing" on the discussion forum. An overpowered main is often the cause of RL28 imbalance, and your old sails if stretched would aggrevate this. All RLs need to be sailed as upright as possible to minimise weather helm.
RL28's built in survey do not suffer any imbalance problems although they sometimes feel slower - perhaps just their extra weight.