I'll be honest with you on mining... While the S3 or the S3+'s are tanks you have to have 2 or 3 of them to have at least 1TH. I have 2 S3+'s personally and they run fine but don't expect ROI at all on really any hardware now. Keep it as a hobby otherwise being all about making money or a large amount of profit will take its toll. You need to take into account how much you'd be spending on electricity as well.
Thanks for the input ,
At the moment the current costs im being offered the S3's for
I can achieve ROI in 3 months excluding electricity costs,
I doubt you can. And leaving electricity costs beside is not smart either.
Somehow i think you never heard of the concept of rising difficulty. When you want to check if you will get ROI really then try out this form: