Geisha Girl.
I see no problem with a basic CPL holder with 150-200 hours doing a CIR on a single of multi. I have put through many with these hours over the past 10 years.
The RAAF graduation their pilots with 210 hours and their CIR equivalent - only more searching in terms of limited panel and unusual attitude recovery training.
Regardless of whether a pilot has an instructors course behind him/her or not, it makes little difference in my experience.
The vital factor appears to be the experience level of the instructor who is teaching you the CIR. If he is experienced and has an easy manner then you will absorb the instruction better and save costs.
Certainly there is no guarantee that you will walk into an IFR job with 200 hours and a CIR. But there is no doubt in my mind that you will be far better equipped to cope in event that you inadvertently get caught out in bad weather while flying VFR. For those that will instantly leap in to criticize that last sentence - I repeat the word inadvertently
On the other hand it has also been my experience that those going for a CIR and who have been taught by non-instrument rated instructors the sequences of VOR and ADF orientation for purposes of night VFR, most have had to start again from scratch in these sequences perhaps because their previous instructors - being VFR qualified only - were not really sure how to teach orientation exercises in the first place.
Just make sure that if you intend to go for a CIR then avoid getting sucked into doing most of your training on a twin. It is highly expensive and because there is no twin command time while under training - only dual - the value for money is less.
Spend as much time as possible in a synthetic trainer before flying your first dual IFR flight. In fact try and reach instrument rating standard on the ground trainer first. This can save you lots of money providing the ground instructor knows what he is about.
In my view, the learning phase of instrument rating training should be on the synthetic trainer and something like a C172.
The twin training should be mainly concerned with the asymmetric skills needed for the IR test. That should be no problem for a reasonably competent 150-200 hour CPL.
Certainly CIR training is much more enjoyable than an instructors course and the thrill of a well flown ILS with needles centred all the way in IMC is quite something. Beats a well pattered glide approach in a C150 any time!
Go for it...