I would definately go for something gentle because a 6 month old isn't behaving that way because he is naughty. he needs you and he needs the closeness of his mother. He is still a small baby and cannot yet understand that you will come back.
The gentle removal plan that seems to work so well (and with hardly any crying) night work a treat...
First he can sit on your lap and play... then a bit on your lap... than next to you... and so on. I wouldn't do it toooo slow though because he might start crawling soon and then it may be harder to actually be consistent, iykwim