I had a gazillion sweeps with my first, and they did nothing (I don;t think she was remotely ready to come out, actually, but that's another story...) but on the basis of that and some reading around into induction I've done, the consensus seems to be that sweeps only really make a difference if you are pretty much ready to pop anyway... I think if your baby's not ready then it won't do much anyway...
So I don't think it's really messing with nature that much ? just giving it a little nudge, really. And if you're fed up and in pain, and didn't find it particularly unpleasant last time, (some friends of mine seemed to find them excruciating - I just found them slightly undignified...) then it's not such a drastic intervention, really, and so I don't see that you've much to lose.
I don't, btw, think that sweeps make much of a difference to the kind of labour you have (certainly not in comparison to other forms of induction) from what I've read. So I wouldn't let that worry you too much.
That said, I think a degree of frustration and impatience is understandable and natural, but not necessarily a reason to do anything. I know a lot of the decisions I made last time were due to this more than anything, and I wish I'd had the patience just to let things run their course...
But it sounds like your really finding it difficult, and I think if I were you I'd be inclined to give it a whirl and see what happens...
But look, I'm just someone who had every kind of induction intervention there was last time without much success, and as a result I've read a bit around the subject. I'm NOT and expert, or medic, or anything like that, so I just want to add a disclaimer that someone else may come along and say I'm talking out of my arse, and I'm quite happy to stand corrected should that be the case
In short, examine your motives, but it's not that drastic a thing...
Here's hoping it all happens naturally in the next few days for you anyway, hey?!
db
xx