The data shows only 65% matched within one day at market rate. The problem is if too many people use the priority rate then it will continue to drag down the market rate.
The problem is also that it is a one way ticket - you can't drag the market rate back up if they simply use the average of the last 30 days and your options are market or lower...
The way it is going they will end up with rates as low as Ratesetter. Maybe Growth Street could consider introducing a 3rd option, a low priority rate 0.1% above the current market rate. At least that way investors would have the opportunity to pull rates back up.
I no longer use the priority rate, now that I've realised what effect it has. It means that my funds are likely to lie uninvested for 2-3 days every month, earning no interest. Despite this the market rate is likely to still continue to fall if enough people do opt for the priority rate