There's some helpful info on this page.
http://golf.mizunoeurope.com/irons/
No set range a player should or shouldn't play one model over another. if you're looking to improve there's no reason you couldn't play the MX-300's.
There's a difference between a 17 hcp who's been a 17 for 10 years (more suited to the MX-200, MX-1000) and a 17 who has some room to improve (probably MX-200's or MX-300's).
Also bear in mind that with all the long iron replacements available (MX Fli-Hi), you don't need to bail out to the most forgiving set. If you really like the idea of the MX-300's, you can always start your set from 4 or 5 iron.
http://golf.mizunoeurope.com/irons/
No set range a player should or shouldn't play one model over another. if you're looking to improve there's no reason you couldn't play the MX-300's.
There's a difference between a 17 hcp who's been a 17 for 10 years (more suited to the MX-200, MX-1000) and a 17 who has some room to improve (probably MX-200's or MX-300's).
Also bear in mind that with all the long iron replacements available (MX Fli-Hi), you don't need to bail out to the most forgiving set. If you really like the idea of the MX-300's, you can always start your set from 4 or 5 iron.