Setting transaction-fee in MultiBit by editing multibit.properties

You asked a question that is very political to the technical Bitcoin community. Jim Burton (the author of Multibit - Jim618), is saying that you can't currently tweak the "multibit.properties" file unless you want to fork the the open source code base. (You have to be a software techie to do this.) It looks like a future version of Multibit may enable end users to tweak the acceptable transaction fees with a slider bar based upon a fee per transaction size rate.

Because the limited number of Bitcoin blocks (~150) that successfully get added to the public Bitcoin Ledger (the Blockchain) each day, Jim Burton is using Multibit to maximize the chances that a Multibit customer's transaction gets added to the Bitcoin Blockchain in a timely manner. He is currently doing this by having Multibit dynamically compute on a per transaction basis a Quality of Service (QoS) fee that pools and miners processing the transactions understand. Because of profit motives, mining pools and miners will put the Multibit transaction at the front of the line. Thus maximizing the odds of transactions being completed, i.e., committed to the Blockchain.

Peter Todd stepped in because he does not want to see the Bitcoin block size grow too much, and for good reasons... (Ah, the politics...) From Jim's perspective, growing the block size, will temporarily solve the QoS dilemma (the Bitcoin payments system current transaction processing ceiling is under 7 transaction per second, Visa can handle peak loads of 20K TPS) to make Bitcoin transaction fees more understandable.

In summary, you asked a question that is fundamental to the growth and adoption of Bitcoin. If Bitcoin is to scale, techniques other than wallet transaction processing QoS mechanisms have to come into play. This topic raises Peter Todd's ears and mine. Bitcoin speculators will be watching transaction processing scalability topic like a hawk...