Depends how you use the Sterno. To just about boil 1/2 litre of water can sometimes take around 15-25 minutes. This can be improved somewhat.

http://www.youtube.com/watch?v=vhpELizxNKk

I have been able to get a rolling boil of 1/2 litre of water using gelled Methanol by using a Vango PowerEx Kettle, a Wild Woodgas Stove MK IIt stove and a Jam Jar lid after placing a couple of tea spoons of the gel onto the Jam Jar lid, down to around 5 minutes.

Methanol Gel will typically have 18 MJ/kg
Ethanol Gel will typically have 28 MJ/kg
Hexamine will typically have 30MJ/kg

So Gelled Ethanol will typically be 30% lighter.

The Firedragon Gel and blocks are expensive by comparison to chaffing gel fuels and fuel for conventional alcohol stoves and it will light with a strike from a Ferro cerium rod and it performs well even when compared to Hexamine, Trioxane and Greenheat gel (Military specification fuels). It burns cleaner than methylated spirit, Hexamine etc and is less toxic and cheaper than Hexamine and Trioxane.

Firedragon gel is also available in 1000ml making it around half the price of 4 x 250ml bottles.

There is also available 1000ml gelled ethanol Vango F4 fuel for an RRP of £8

http://www.youtube.com/watch?v=nM5rPqxW6Xg

Zip fuel is another cost effective fire starter available at local supermarkets.

http://www.tesco.ie/groceries/Product/Details/?id=257570627