The downside is, with the commute, it would mean I basically wouldn't see my babies from Monday to Friday except for maybe an hour before bedtime. This makes me feel a bit ill.
I did this for 5yrs from DS was 3. Sometimes I didn't even see him at bedtime (I would leave at 6am and not get home til 10pm or would even stay away overnight).
Good stuff:
I was doing something I loved and gained experience I otherwise wouldn't have got, my business certainly wouldn't be where it is now if I hadn't done it.
I made some really good friends for life.
I made some solid client contacts and got my name out there which has helped my business.
I got lots of "me time" and never felt like I was "sick of" DS (or DH).
DS is confident and outgoing, certainly not tied to my apron strings. Is this down to separation? I don't know.
Bad stuff:
I was constantly tired from the long days, and sometimes a nightmare to live with.
Sometimes I liked the "me time" a little too much, there were occasions I thought "I don't want to go home and get nagged/pestered/no say over what's on TV" but then I gave my head a wobble!!
It was tough on DH, he says there were times he felt like a single parent because he literally had to do EVERYTHING.
DS was always a good sleeper, but he went through a phase after I'd been working away for around 6 months of getting up and coming to my bed 3/4 times through night, not ideal when you have to get up at 5am!! He didn't do it on the nights I was away and DH was on his own, only on the nights I was there, so clearly it was affecting him and he was having separation issues.
In the end DH sat me down and told me I needed to decide what was more important; my business/career or my family because we couldn't keep living like that. He was right and we've never been closer or happier, he saved our marriage with a bit of tough love 
My advice to you would be to only do it if it will lead to bigger and better things, only see it as a temporary measure, as a stepping stone and set yourself a timeframe.
Don't go into it planning for it to be permanent.