"The best traders in the world do not trade AIM - why is that? because they are risk averse, protect their capital and do not want to give their money to the market makers. Unfortunately many people trading on AIM right now will say that I am talking rubbish, and will continue until in 9 months time they have no money left. Meanwhile the market makers will sucker you in - sure there will be some companies you will make money on - but on average the law of probability is against you - hugely against you - especially on AIM."
Traders avoid AIM because of the generally large spreads. I assume the 'best traders' also avoid it because it's impossible to get inside those spreads with the sort of numbers they play with.
Investors like me, those with a medium or long term view, can live with it by building up their stake using smaller buys.
PDX will succeed or fail based on the technology and the management. My research suggests the former & I've invested accordingly.