Today ace3ds plus official site has released the update patch for 3DS V4.4.0-10. so if you have the ace3ds plus card, just use the update patch to update your card, then your ace3ds plus will be working on your 3DS V4.4.0-10
more info about the ace3ds plus, check here: buy cheapest 3ds flashcart ace3ds plus for your 3ds dsi and DSL-dsflashcart.com
download: ace3ds plus update patch for 3DS V4.4.0-10
Wood firmware for ace3ds plus
make sure update your ace3ds plus before you update your 3ds console. and also use a ds console to do the update, if you plan to buy a flashcart. just buy a preflashed one, so you dont need to update it when you receive it.
ace3ds plus update guide for 3ds V4.4.0-10
Download the latest ace3ds plus firmware and the update patch from the links above, and then put those files in the root of your sd card.then put the sd card the your ace3ds plus flashcart in the ds console, turn on and run the update patch to complete the update.
cureently there are 3 cards can work on the 3ds latest firmware now, r4i gold 3ds, dstwo, ace3ds plus, feel free to choose any of them for your 3DS.
Do yourself a favor, don't buy crappy flashcarts.