I think the number 1.231 is only registered in MT4, but there is another trading platform like cTrader, Ninjatrader, not all broker using Metatrader as a trading platform, some of them create own trading platform.
Yes, I think traders will make research when they looking the broker, reading reviews in forums, site reviews, etc, but when traders already finding and use reliable brokers, they will stick with its company.
Retail brokers actually don't differ from other brokers. The main idea of their existence is that they offer some exclusive assets for trading. One can state that all brokers are the same and I can partly agree with such an opinion. I believe that brokers who are out of service nowadays just couldn't handle their main task. The main task of them is to satisfy the need of traders, because when a trader is happy, broker receives money. It's quite a very simple statement and is clear to understand. I believe that brokers should never betray their occupation, because they provide lots of traders with money, via connection with market.