I agree with rjack. Every step of the way past singles diving doubles your costs. First, you need double the tanks, bands, manifold, wing, maybe a different plate, and harness, regs, hoses...then double the cost of service for that equipment, and fills...and all of a sudden with that much gas, NDLs creep up on you quickly and you're paying even more for nitrox...all of this before you even touch tech...
You also mention you'll be traveling with your gear; chances are you won't be traveling with doubles gear. Until you get to a point where you're not scrimping for cash for each upgrade, I say stick with diving singles, and only move on to doubles/tech if get bored of the dives available to you.
You also mention you'll be traveling with your gear; chances are you won't be traveling with doubles gear. Until you get to a point where you're not scrimping for cash for each upgrade, I say stick with diving singles, and only move on to doubles/tech if get bored of the dives available to you.