ESA or CA

Hi, I was wondering if anybody could give me some advice, at the moment my wife is currently in the support group of ESA and also is entitled to HM and MC... DLA indefinitely, (although I am aware from your site that they can reassess this at any time)
I am her carer she suffers with numerous problems including arthritis of multiple joints, urinary incontinence, severe anxiety and depression. She had a terrible time at her last "Medical" in October last year when she was transferred from IB to ESA, we had to complain about her treatment and she was placed in the SG.
We have just received the forms again and went to see a welfare rights advisor who filled the forms in for us, although the resources on this website are excellent we felt after her last ordeal it would be wise to have external face to face support, she is in a terrible state from the moment the letter comes and then worries about the next time when it is over, I explained to the advisor that this ongoing process is making her anxiety and depression so much worse and she is worried sick over the prospect of WFI and all that comes with them.
The advisor did suggest that there is an alternative were my wife could claim Income support and become a full time carer for our autistic son who has just been awarded HC...DLA and then she would not have to worry about the whole ESA procedures, or there is obviously the option of appealing any lower award she may receive of ESA but again with an appeal there would be the distress factor.
My question is are there any draw backs to taking the option of becoming a full time carer to our son and changing her claim if she is not placed in the SG this time? our sons award is until 2017 although he is 16 in 2015 so I don't know if they will transfer him then onto PIP and also how many WFI will she have to attend if she becomes his carer and will they be the same if she is a carer as they would be on ESA? I am assuming from what I have read that even though our son is at school she cannot be forced to attend a Mandatory Work Placement as she would be a full time carer.
The welfare rights advisor did suggest she should remain on ESA but I am worried the stress is too much for her.

Thank you for your reply Gordon
I was told financially the CA and Income Support would basically be the same as we receive now, in the longer term I am worried about the effects that the (probably several) medicals and forms ect are having on my wifes mental health,
Is ESA more secure than CA?
If she does claim CA and the award is removed at some point in the future would she be able to claim ESA again?
does your ESA award have a positive influence on a DLA/PIP claim?
As far as WFI as a carer are they basically the same as she will have to endure on ESA?

Sorry about all the questions but you tend to think of these things afterwards

Thank you Gordon, that gives me something to think about and your time is much appreciated.