Disadvantages of dual sim device with single sim installed

[-Jigsaw]

Hello, I am looking to buy a new smartphone, but stores in my country only have the dual sim version of it. I was thinking I could buy it either way and use a single sim but a friend claims that the disadvantages(battery life, networking problems) of dual sim phones still exist while using only one sim.
Is this accurate? Maybe manufactures will drop some features in order to make a device dual sim capable?

-George

*The smartphone is Alcatel Idol X+

 

[madmatt30]

Nah mate - with 99.99% of dual sim phones ive encountered having only 1 sim installed completely disables the other slot - either automatically or via network setting menu (assuming this is android os)