Hi Ben, welcome to the forum.
The main aspect of the templates deals with the workflow and the fact that everything is already setup for you. Is it the "magic bullet"? Some would say yes, some wouldn't say anything at all because they're too busy writing. Will you be stoked and have an end in sight with the learning curve? From the sound of things, absolutely!
I'm not sure what you have been "missing" in the past that relates to your time, but having all the VDL instruments pre and properly defined ahead of time will definitely save you many a common headache when it comes to working with the under-the-hood aspects of integrating sample libraries with Sibelius.
Since you mention full band scores too, I have to recommend you consider one of the bundles (either SE6-VDL Bundle, S7S-VDL Bundle, or S7S-SE6-VDL Bundle, depending on how soon you think you may upgrade to Sib 7, if at all). Again, having it all done for you in advance goes a long ways in getting some actual writing done.
And lastly, from now until the end of the this month, use the coupon code YEARTWOSALE to get 15% off your order. So now may be the time to save some time.
Let me know if you have any other questions.