Disctrionary and IIP Trusts

[prophet07]

I have a client who is considering changing the trust set up by his late parents, where his children are sole remaining beneficiaries, into an IIP trust.
This was originally an a&m trust.
Trust income distributed to children in 2010/2011 was taxed at 50%.
What are the tax implications of doing this now, or should he just continue until the children reach 25 ( 1st is now 20, 2nd is 17) when the beneficiaries become entitled to capital