I use Kotak ActivMoney for IPOs like SME where you never get allotment 😂Linked FDs will be better if those are not broken for UPI mandate/ASBA and where you don't get allotment. If you get allotment and your objective is listing gain, then OD is better.
And FDs break only if I get the allotment and the amount is deducted. Even if the amount gets deducted I can credit the same amount or higher within same day before midnight the FDs won't be broken and they will continue.
Kotak & I think ICICI as well has this facility and they do Sweep In FD settlement at midnight.
I earn 7% on Kotak that's 1% less but can use 100% of the amount and do not need to pay any interest.
I feel OD is great if its backed by Stocks/MF or illiquid property. I don't get the logic of FD backed ODs for IPO.