Hi sensible i agree with dave,if you can sort out an agreeable realistic,settlement with your creditors why pay the middle man,use the money you would have paid in ip fees to other realistic settlements.
I also,would take on board what Dave states regarding interest rates,i think the way things are going they will continue to rise,glad my mortgage is fixed for another 4 years,but in saying that hopefully by the time i come to renew my mortgage it wont be a massive shock finding the extra,if its that much higher,than im already paying,any way it wouldnt hurt to test the water and contact your creditors and find out what kind of reaction you get,just let them no you are currently with payplan trying to get an iva sorted but you are just enquireing what sort of settlement they would offer if iva isnt successful,may be worth a try,you can always stick with payplan if its not viable.
Goodluck