Pneumatic suspensions make a difference at high speeds and with dense loads. With the kind of speeds we typically see in IR, well designed spring suspensions have shown excellent performance with smaller maintenance costs. Also, the pneumatic suspension is only in the secondary stage, mainly contributing to ride quality while the primary suspension ( spring suspension in the original LHB technology as well) takes care of most of the large forces on the coach. And with our usual speeds, spring suspensions similar level of comfort as do pneumatic ones.
As far as I know, no pure LHB rake has pneumatic secondary suspensions. The Double decker coaches (derivatives of the LHB coaches) do have secondary pneumatic suspensions, as...
more... do some of the hybrid LHB coaches ( LTT-GKP SF 12542 is one I remember) , which have pneumatic suspensions in the secondary stage of an ICF bogie. (This also served to increase the maintenance time and construction costs for the HLHB, which combined with it's less thn expected performance, led to the concept being scrapped).