As an IMC and IR instructor I would definately second the idea of currency being the most important thing in keeping you alive, rather than the type of rating you hold.
I have flown with experienced IR holders who have almost fainted at the thought of using an RBI and "lesser" IMC holders who would have been fine no matter what was thrown at them.
If you are trained properly and fully, then you are unlikely to finish the course in 15 hrs. It is the same for the PPL itself. 45 hrs is a legal minimum, but not IMHO a realistic one for safe and competent pilots.
I would suggest that all PPL's do an IMC rating, if only to give you something new to help keep your interest in flying. It can be a valuble safety aid and I'd rather someone had it than not, but it is not a get out of jail free card. If you have got yourself in trouble it gives you another possible exit, but that is all. It won't keep you alive if you are monumentally stupid, but it might stop you from putting yourself in that position in the first place.
Go to a school that can offer you training in a properly equipped machine. All ours have full equipment, with only one not being airways equipped. Having the extra kit is pretty essential in my eyes and I would never consider teaching someone without a full complement of aids (that work aswell!) Unfortunately many other places will try and teach on a/c that are eminently unsuitable.
If you are going to do the course, then you may as well get some use out of it, so find a school where they have the equipment that you will use for real and learn how to use it properly.