Hi jakkijax
For claimants in receipt of ESA Support group and receive disability premiums will be worse off claiming UC.
This is one reason why the government brought in TP, to get TP you have to be invited to claim UC, DWP will send you a managed migration letter, if you claim UC through Natural Migration then you will not be able to get the TP element.
If you are eligible for TP then you should be no worse off claiming UC than legacy benefits.
We cannot answer your question about your friend as we do not know their circumstances or yours.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
