I've heard it won't get supported for a long time but we're not sure how many changes there are between the 2 versions
I have a 3DS XL on 9.4 and I don't intend to update any higher although I'm not going to use Gateway on that device (i'll use it on my N3DS XL v9.0)
I don't think you need to update to play any of the current games that are out at the moment either (shouldn't need to update for MM 3D or MH4U) In short - only update if you absolutely really need to, 9.5 GW support won't come in a long time anyway
They also don't support 9,4 on sysnand and that's not even coming soon™. There's not a problem with not updating now (unless you want eshop), but when games come out that require 9,5 to run, what will you do OP? Will you want to keep waiting for when (or if) gateway finally says soon, or will you just want to play those new games? If you are dead set on gateway and aren't even considering sky, trade in your current system for a new one while ≦9,2 is still really common.