how is compared to US M777 ?
M777 is a modular howitzer, which beside they can be airlift-able by medium helicopter (M777 can be lifted by UH-60, you can't airlift AH-4 with UH-60 external sling loading) since they are modular, they can be drop by C-17, C-130 as part of Airborne deployable howitzer. While AH-4 is a light weighted towed Howitzer, which basically the lighter version of M198 the Pakistani is using. (Although M198s are also modular)
People don't understand howitzer would think "This is not a big deal, M777 are only 300 kg lighter than AH-4" but in reality, this is probably the furthest from the truth. The problem of airdropping a howitzer part is that they (the parts) must be durable, which mean you can use them immediately after you drop them from 1000ft AGL. Now imagine this, if you have a light platform, you drop them from 1000ft AGL, you probably ended up denting the parts and you cannot put them together and use it, especially the parts that connect 1 component to another. But for parts to be durable, they have to be made in heavier substance (more steel than carbon fibre or untempered titanium). Which means it would limit the package you can drop per aircraft. And that is the problem.
On the other hand, howitzer like AH-4 do not need to be drop from skies, and they are not modular, which mean, you can easily save weight by making lighter material replacing the heavier steel or iron compound. Even with less dense Titanium, which offer less structure strength, but since it was not a modular system, the strength will be compensated by structure integrity.
think about it like a convertible and a sedan of the same car, Convertible, since they are missing the top, their body and chassis must be hardened to compensate the lack of structural strength, however, a couple does not require a hardened chassis and body because it maintain its structural integrity, thus a sedan can be lighter, goes faster but a convertible is more expensive.
M777 is expensive because the material is heavily treated so they are actually stronger than titanium, but they are lighter than steel, 300Kgs may not be much but if you think about it, it's quite a lot to shred with the competitor, and it's modular.
However, if a country does not have a large airborne dependence or they don't have hills or highland (like most GCC country) then M777 would not be wise for the money you spend, because you basically spend more but got all the advantage negated. If I have a flat environment with some hill, I would probably go with platform like M198 or AH-4 instead of M777, it just not worth the extra.
Airdropping M198
Airdropping M777
