Even if the playing field is absolutely level, I am still in favour of capping the number of foreigners (including PRs) at 20% (possibly even lower) of the total population. This is because of the limited resources on this tiny island. There is a reason why property prices have shot up astronomically. And it is certainly of no help that HDB prices are based on market subisidies rather than real subsidies.
I wish there was some research done on the full impact of the influx of foreigners. Sadly, I think this will never happen as you will no doubt recall the case of the two NTU economic professors.
It is one thing to try to attract the wealthy to Singapore but quite another when the numbers attracted are crowding out the less well-off off the edge of the cliff.