Do you mean the 92FS Compact Type M?

sorry yes the FS also the M9A1 what would you buy? any advice would be great

Well, the 92FS is different from the 92FS Compact (compact has a shorter grip), and that's different from the Compact Type M ("Type M" denotes a single-stack mag with the same grip length as the Compact). The 92FS Centurion has a shorter slide but the grip is the same size as the full size.
I take it your CX4 takes the PX4 mags? If that is the case, it won't accept 92 mags. There were certain runs of the CX4, with CX4s of a certain serial number range accepting PX4 mags, another range that accepts 92 mags, and another range that accepts Cougar mags. So make sure your CX4 is in the range that accepts 92 mags before you set yourself up for another shitey day.
The M9A1 has a light rail, which I do not care for. The regular M9 with the straight dustcover would be my choice, but that's my humble opinion. The 92FS is a fantastic platform, I have an M9 20th AE and a 96D Centurion. Both are fantastic weapons. I say the M9 instead of the 92FS because it doesn't have the wanker warnings on the frame. Some people prefer the 92FS instead becuase it is "updated" with the radiused dustcover, re-radiused backstrap, and other little things here and there that are not included on the M9 because the M9 is still built to the government contract specs. The 90two is pretty much the identical to the 92FS with the exception of the rail, a dovetailed front sight, new trigger guard, and a shock buffer inside the frame.

thanks for the insight. ill have to look into the magazines then.

I own an M9A1 and a Model 92FS Type M. Both are excellent pistols, so its a matter of personal preference.

The M9A1 uses readily available (for about $15.00 each) while the Type M magazines are hard to find (and when you do find them, they cost about $35.00 each). The slide is the same width on both pistols, while the barrel and grip are shorter on the "M".