So here is the final basic build after making some additional changes and additions to my prototype.
Changes from my initial prototype include the new support system conversion on the left arm, the sensor head dog ears (the riptide head I'm using had a single unicorn antenna that I was initially going to use), a railgun grip guard in front of the hand, and dual fins on the calves to further accentuate the increased maneuverability of this broadside variant. My initial goals for this model were to model both the bazooka railgun (thanks again to Kael'yn for the initial proof of concept with the new kit!) as well as the booster nozzle that gives the model deep strike and relentless. There are still a few tweaks I'm planning on like adding a commander's honor blade (it is technically for a Farsight Retaliation Cadre after all) to both the broadside and the Riptide (which must now take them whereas they were previously not an option) but I'll have to see if I can get a fair price on the bits. Likely in the intervening period, I'll probably think of a few more tweaks in the meantime. Below is the fluff that I was developing for my variant model.
XV-88S "Si'ts-Kree" High Maneuverability Broadside Variant
With the rapid pace of weapons development in the Third Sphere Expansion, the Fire Caste noticed an acute need for added firepower to accompany the more aggressive, long ranged, and fast paced use of Crisis Suits exemplified by the new Retaliation Cadre doctrine. In traditional Fire Caste doctrine, the broadside filled this role quite honorably but it lacked the manueverability necessary to support faster moving cadres once they deployed from their Orca transports. Additionally, the broadsides were almost completely immobile and unable to participate in extreme environments like underwater or in a vacuum. Recent advances like the Riptide and it's variants have addressed this need for greater mobile suit firepower somewhat but the availablility of this until recently secret and experimental suit is limited and mass production on the scale of crisis suits is cost prohibitive. It was decided by the Earth Caste under the direction of the Ethereals and the request of the Fire Caste to develop a high mobility version of the venerable broadside suit.
The highly efficient coolant system under the powerplant was removed and was miniaturized significantly despite maintaining 70% capacity. It was then placed within the suit torso and coupled with a moderate improvement in the powerplant. In its place, a single large thruster nozzle was placed capable of short intense burns along with some additional flight stability fins on the legs. With the thruster is not powerful enough to actually propel the Broadside in sustained atmospheric flight, it is capable of arresting the suit's fall when air dropped from a moving Orca as well as propelling the suit both underwater and in space at moderate speed. During normal operations, the improved powerplant and targeting software allow added mobility while simultaneously fully charging the railgun and plasma weaponry, previously not consistently possible without a devastating loss of accuracy. The smaller cooling system is less efficient admittedly and the suit does suffer in the traditional role of sustained full battlefield Hunter cadre support fire. It is however sufficient for the short but decisive engagements that Retaliation Cadres typically engage in.
It was decided to name the variant after an ungainly Kroot end evolution common to their homeworld. The Si'ts-Kree is an ungainly large flightless bird with an abnormally large beak and powerful bite. While technically flightless, it is capable of powerful jumps that allow it to reach perches high up in the tree canopies that would otherwise be impossible to reach for a creature of that size and bulk. It then typically drops down on the unsuspecting prey and kills it with its powerful beak.