Does it makes sense to use delivery margin?

Most of the brokers who provide delivery margin like Angel broking charge around 0.05% per day as interest on the margin funded which is around 18% p.a.

This seems a lot given that personal loans seems way cheaper than this at 10% p.a. I understand in loans the EMI starts right away and will include principal component as well but still it is way cheaper than delivery margin.

Has anyone used delivery margin service from any broker, do you recommend it?

There is overnight risk. It increases with delivery margin.
It’s not a very good choice for beginners.
On top of that you are paying interest as well.
If you are experienced stock market participant and has a proper system and also ready to pay the interest, then you can go for it.

I have a doubt here, When you buy stocks with delivery margin, will that security go into your demat account or will it go into a pooled broker account (as broker’s money is involved) ?

I think we have to pledge those securities so that broker can sell it in case of non payment of M2M or interest. Not 100% sure on this though.