Using this particular scheme - where you reduce the final ticket price at the final stages of the booking process using the 2 or 3 blue box options - does not change the Avios / TPs you get. So if the ticket was ET restricted you will get 10 or 20 TPs as normal, 40/80 in CE depending on distance. Ditto for long haul.

Unless you have a mountain of Avios that you are a nuisance to you, then this is not a good use of them. Even using them against hotel bookings is better value.