We lose virtually no players to union and only a handful to the NRL, plenty of whom have come back anyway. I've just googled the RU premiership salary cap and it's an eye watering £7m from next season (How the hell can they afford that?) and the NRL cap is $7m or about £4.25m. In reality, what level of cap increase do we need to really compete if they want our players (irrespective of the desire of a player to test himself in the NRL).
In general, RL players at the elite level in this country are very well paid at an average salary for a SL player of somewhere around £60-70k. I know they put their bodies on the line, it's a short career, earn less tan footballers etc. but the harsh reality is that they are pretty much earning every penny the clubs get from the TV deal and a fair chunk of clubs only exist because of the generosity of club owners. Personally, I see no real benefits in increasing it other than maybe a very small number of players staying put rather than moving to Oz or RU (Where the top players earn £1m+) at the expense of the competitiveness of the comp and the possible financial hardship of some clubs