I'm petitioning for unreasonable behaviour.
I would be very surprised if it cost you more - mine certainly won't. The paperwork is the same and there should be no differences in preparation time for a solicitor, the court costs are the same.
I was told that only a fool would fight a UB petition no matter how unfair it was, as it just generates costs, so it's no more vulnerable to a legal fight than the other grounds.
Hope this helps.
my wife left me to move in with her new bloke and before i could put in a petition for adultry she put one in for ub against me, everything she put was lies, i saw my sol who said it did not matter, he put i disagree with what she said but would not defend it as i wanted the marriage over. he said that i would not have to pay her costs since i was not defending and she had saved me £300 by her putting petition in. he also said only the solicitors and court see the reasons so it did not really matter what is said. he said that bit should go through no problem and shes made it clear she does not want our son on the form for arrangements for children. he said the only problem will come with the financial side as she is adament the woman should get the bigger share, but hes told me i should as i will be bringing up our son, so will have greater needs. he also said she can not get sm as she is living with new bloke and she as no housing needs as this is sorted, so everything in my favour.
not sure if this will help with what your asking, and i will be interested to see what others say.
I to am petitioning for UB although I get legal aid but I would have thought the solicitor would have had to tell me if it was going to cost more than other "facts" as I am liable for the costs if I get anything in the financial settlement. It will be good to see where this one goes. I can't see why it would cost any more - all divorces cost different depending on the needs re: sorting out finances & children and whether it is defended or not. I'm waffling so .....