Gearbox Shim 6 speed

I've been reading about the shim mod for the vrs 6 speed box and I know I have a whiney 3rd gear especially on deceleration. I actually thought the police were behind me the first time I tried engine braking in 3rd from high rpm.

I also find it slightly difficult to engage 1st gear unless I push clutch down and wait a few seconds when it will slot in better.

Reverse is the same condition as 1st. All other gears seem fine although sometimes 5th is a little notchy but I think thats down to me being picky.

Is the shim mod the likely solution to these issues? I know its cheap and easy but thought Id see if this sounds like a gearbox or clutch issue with the 1st and reverse gears. Its not a major problem ive just learnt to live with it and show some sympathy when engaging 1st gear (unlike other people who have driven my car who tend to force it in as hard as possible)