This. Glass cockpits are WAY more complex than steam gauges. Sure they give you more tools as a PILOT but as a student they just add more things to learn and more things to have to demonstrate that you know how to use. I'd tack on at LEAST 5 hours MINIMUM because of the glass and this assumes you go nuts with home study of the glass cockpit manual.
If at all possible skip the glass (they're usually more expensive to rent, too) and this is coming from a computer loving engineer who really enjoys flying a glass cockpit plane.
I don't understand why people separate the training phase from the pilot phase. First off, it's not the glass panel that takes any particular learning, it's the radio that drives it. If you have a 430w in a six pack plane, the learning curve is pretty much the same as a G-1000. Now if you want to go to a a non GPS plane, ok, you don't have to learn how to use the box. However, if you are planning to use the GPS/Glass plane after you get your license, then it makes no sense to avoid it in initial training; in fact it makes poor sense as you will need additional training after you get your license to become proficient or even safe with it. Makes more sense to start with the equipment you plan to continue with, that way when you have your ticket, you have 40hr of experience with it and have proven ability and competency at operation. You and your passengers will be safer if you start with the equipment, and THAT is the point of the training, NOT getting your ticket with the least time and effort possible.
Train like you fly.