I don't know about the specific .X3A file you're referring to, but I do know it's possible to load 1gb+ .X3A files into Montage. I create them in John Melas Motif Waveform Editor and they work fine on my Montage no problem.

Thanks for your reply Joe.
I'm a John Melas' software user since I was a S90ES owner, then I moved to Motif XF and recently to Montage.
.X3A is a Motif XF All File, the file format Jamal's Flash Sounds are sold.
Well, if something goes wrong, I can load those sounds into my Motif XF.

If you are purchasing a Library for the Montage it should expressly list compatibility with the Montage particularly if they are charging top dollar “almost 200$ on a single sound bank”

If you are unsure about a sound Library and it’s compatibility contact the author, this way you have recourse if it is not compatible. Sounds strange to me ... to pay top dollar I would expect to get a .X7U and/or .X7L File (native MONTAGE formats)... here’s why, the MONTAGE is about eight to ten times the synth engine the Motif XF was... this difference is not just in Wave ROM size but it is many times the engine in terms of programmability... a file in Motif XF format .X3A will only have two Assign Knobs programmed per Part, it can only have six Control Sets per Part... contrast this with the eight Assign Knobs per Part and the entire Super Knob Assignment System, plus the sixteen Control Sets per Part.

If an author is making Libraries available for the MONTAGE you might expect to have that data take advantage of all the new functions on offer - which would mean it comes in a MONTAGE native format. If you are buying it for your MOTIF XF, no worries... the author created it in .X3A and therefore it should be able to be used in that keyboard.

for data specifically available for Montage you can visit www.YamahaMusicSoft.com or www.EasySounds.de

$200 for 1 sound Lib. That is just too much for one lib.
Unless it makes a good song into a Great song. And U do that Not the Lib. of sounds.
I agree with Bad Mr. Look at Easy Sounds. And YA sounds. I am sure. Near all of what U need is There.
I have 6 easy sound lib's and 2 of the Not free Ya sound lib's.
The only Diff I can tell You.
Easy sounds. I can not run thru the Performances. Without Stop-ing and playing it.(each one)
Peter Has a true gift for making Things sound. The way You are hoping for.
Hell I even play along with some of his performances. That Are So not me. Just because He captured something.
That makes You want to play it.

Bad Mister and Tom, thanks for your replies.
Luckily I bought all the sound libraries for Montage until now avaliable, except the ones which contain tonewheel organ sounds, not suitable for the music I'm aiming to compose.
All that said, I don't actually know if I'll buy that particular library made for XF, because loading into Montage requires some reworking and reassigning controllers to take advantage of the newer synth engine. On the other hand I don't know whether, once I'm more into Montage, I'll get rid of my old faithful Motif XF or not. All in all it's still a workstation full of resources.
In the meantime I'll keep playing and experimenting with FM-Xpanded which is, IMHO, perhaps one of the best soundlibraries ever made for the Montage.

Reading all this I'm happy with my montage, That if you bought a sound library you don't have the pickle as with a Kronos
which lets you install it on one keyboard only so to fiddle through hoops and tosses. Oh and FM-X rules baby.

Here is an update: https://www.yamahasynth.com/forum/gospel-musicians-library-updates

Regarding the cost - note that Jamal has tons of great philanthropic work on Youtube with free videos / tutorials on his focus genre of music (which has many crossover points to other genres). He is a passionate player with fantastic chops and lots of well-balanced loyalty to Yamaha. Even though Jamal appears partial to Yamaha - he's no "fanboy" and will be critical where it is warranted.

Having sound libraries from someone so passionate and who "drinks his own Kool-Aid (tm)" and who is active in the online community is certainly an asset and worth considering how much that extra level of passionate/access/artistry is worth.

Speaking of "fans" - I'm a big fan of his work (software co-development) and appreciative of his gear reviews and playing tutorials. If there is material which is useful to your gig or studio, consider the dividends which can be returned by supporting his efforts.