In my workshop/warehouse, I recently fitted LED tubes in place of the all of old 40W/4ft flouro tubes. They fitted straight in place using the old batten fittings.
My quarterly electricity bill has gone down from over $1200 to around $320. No more old flouro tubes for me. The electrical utility companies are 'raping' us, even though the carbon tax is now gone we are still being stiffed for renewable energy targets.
I would fit either LED batten fittings or LED high bays.
Dr Terry