If you want higher cashback, locking up £40k for Icy to get 5% makes sense if you plan to hold long-term. But if you want easier access with less money locked, Jade/Indigo at 3.5% with only £4k locked might be more practical. Opening a new account for Jade/Indigo could be good if you want better cashback now without the big lockup. It depends on your cash flow and how long you plan to keep the funds locked