A adapter is just weight and another thing to fail. You don't have to worry about losses of an adapter, usually the bigger problem is it being lose, falling out, etc.
Be careful with the use of the word converter. Adapter is just to get around the physically different shaped pins. You do not need to convert electricity as the Powerports all are universal in the electricity they accept, only specific to the plug. Some devices (say hair driers) only work on a specific voltage/amps and they do need converters. You do not need a converter, only the plug adapter.
A good system to begin with is the US type of Powerport2 as its folding pins, so less sticky out jagged things in your pack, and then attach the country plug adapter to that.
I visit UK fairly often and I actually travel around UK with the US Powerport, a US extension cord and a UK plug adapter, the reason being USA extension cables are thinner, they end with 3 sockets, the UK adapter over the US plug is the same size as a UK plug, and I can use 3 USA chargers, all in a far denser and lighter package than if I did it all the UK way.
USA things also tend to be lower cost than UK things.