I've found a temporary fix - I really don't know what the huff is about.
So far I've changed 5 files:
includes/templates/your_template/templates/tpl_modules_create_account.php
(To change whats displayed in the gender area)
includes/modules/create_account.php
(To loosen up on the validation from the gender fields)
includes/languages/english.php
(To add new language constants for the new gender options)
admin/customers.php
(To change the gender field to a text box)
admin/languages/english.php
(To change 'gender' to 'salutation' to avoid confusion)
I also increased the size of the customers_gender field in the customers table.
I realise there are some other things to change like the account details page, but there's no way that was a big huff.
Awaits a flurry of payment gateway related problems:lookaroun