It might be worth a try, I think from memory which is not brilliant
the 20 blade was quite a bit cheaper than the 26.
If you are prepared to lay out the money and give it a try it will save you money in the long run.
I`m sure you're aware that some coats once clipped especially the blacks and the fact you're girl has been spayed may mean you will never get a really flat finish.
If you decide to try the 20 blade, let us know how you get on
Tracey