IMHO, it would be like cramming for an college exam (wrote memory) the night before only to "auto-dump" most of it after the test.
Can you learn enough in that 10 day time period to pass the tests? Probably. Is it useful, practical, real world knowledge? Probably not.
Ratings take time and effort to complete and time is also needed to assimilate and to practice the information just learned to be able to put it into practical application. The instrument rating is certainly one rating you don't want to shortcut! Again, IMHO.
my CFII did the PIC course where they come to you. He's only one guy, but he is an excellent instrument pilot and so far has never gave me bad advice. He liked the program, and I ddid buy the Peter Dogan book... well worthwhile.
I did a 10 day course that I finished up in February. (look at my previous posts for the details) Before I started, I did take the written and had about 6 hours of hood time. It was quite a bit to do all at once, but I don't regret it. It is certainly something you have to keep up with once done so you don't forget the material. I chose this route because of scheduling conflicts and the seasonal nature of my job. I feel comfortable with my instrument abilities and was able to log a good deal of "actual" because the weather was horrible during my training. However, I will continue to go up with my local instructor or safety pilot in VFR to hone my skills. I especially want to go up and get more dual training in GPS approaches before doing those solo.
A friend of mine used to be a CFI at one of those places, he told me that most people who go thru those sorts of programs are pilots who own an airplane and are getting a instrument licensce in order to lower insurance or something to like that.
They are not pilots who actually go flying in IMC, and with this type of training they shouldn't. An instrument rating in just 10 days! come on!
I did mine in 10 days. all it takes it total dedication and submersion for those 10 days. I higly recommend that you go to a place / CFII that specializes in 10 day courses. the place that i went to included lodging in the price and was cheaper than my local FBO. make sure that you have your written done before you go.
I am going to do the same, except I will get my IFR rating in 14 days. I have spoken with many and at least 90% of my contacts think it is totally possible, as long as I take my written before hand, and get familiar flying in those conditions on the simulator (FS2002) before hand.