Replacing selector forks and drum

[Fazerider]

... Would you suggest not doing this until it starts jumping out of second gear?

It's best to sort it before it gets bad. Every time you get that grinding noise it damages the dogs on the gears, if they get too badly rounded off the bike will jump out of gear and the solution then is to replace them... that cannot be done without taking the engine out and splitting the cases.
I had a problem engaging 1st and 2nd and thought replacing the forks and drum might be the solution.
My experience of doing the job is here:
http://foc-u.co.uk/index.php?topic=13507