I say save the lesser advantage just a little longer, we can use it to improve the accuracy of our missiles. Maybe.
Anyways, here's a couple of design ideas:
Turbo Rozer
The turbo Rozer is an advanced Rozer, with the ability to produce more advanced caustic agents that it spits out onto stone to be dissolved, and hardened teeth to crack through stronger stones that the average Rozer can. More importantly is it's ability to derive nutrients from even the least likely materials, leading to much less waste so it's tunnels are not self-sealing. The cuticles of the Rozer have been adapted to automatically line the tunnels dug by the Turbo Rozer, creating smooth road-like surfaces for other units to travel along. This makes use of the rozer glue and foamceramic to stick the plates to the tunnel edges and detach them by creating purposely thin and weak lines of material and then snapping them off, rather than having to chew them off.
What makes the Turbo Rozer, well, Turbo, is it's ability to basically turn it's face inside out and chew at the whole tunnel around it, rather than directly in front of it, and rather than slowly digesting everything, compress its waste down into dowels of extremely dense material, firing them out of it's backside as it rapidly chews a tunnel large enough for multiple Stymphalian Crabs to walk down at once. The rapid excavation mode does tire the Turbo Rozer out, so it can only do so in bursts before returning to a more standard excavation method, but it does produce results. The dowels it produces can then be lifted by units with grasping limbs such as the crab units and carried out of the tunnels, or wielded as very heavy clubs. The psychic punch ability of a stymphalian crab can even be used to launch one of these dowels at high speeds when a polyp missile won't do.
Esoteriport
The wings of the Aeroplanar are refined wider, improving on the ability to glide. It's body, too, is larger and wider, but flatter, to better take advantage of close range telekinetic wind bursts. The ability to produce lift has been refined to allow for more powerful bursts, so that it may spend long periods of time gliding without psychic assistance in between; although constant use at lower levels is still an option. It's legs are a significant change, each one having a powerful set of grasping digits which can pick up smaller units such as grubs, rozers, or medusa crabs, even stymphalian crabs... though larger heavier things like boulders cannot be lifted, it can in general carry about 4-6 units, depending on weight. The legs can then curl up and hug the units into a depression in it's body, presenting a more aerodynamic profile while transporting it's allies back and forth.
For defense, the Esoteriport refines the Planar Lance into a point defense, able to sense anything traveling towards it and launching psychic threads outwards to spear them, then expanding a burst of energy at the end of the thread within the pierced object to blow it into bits. Right now this is only useful for errant stymphalian missiles, but who knows what the enemy will come up with?
Ironclad Crab
The polyps of the Ironclad Crab create a spray which does not neutralize toxins - rather, the resin-like hardening of the original secretion is improved upon, taking inspiration from (though not directly copying the methods of) the rozer's foamceramic to create a coating of a spongey and flexible, but hard and resilient material. The Ironclad Crab is capable of psionically moving this before hardening to create complex shapes, or to squeeze the air out of it to create even harder, even more durable but much less flexible surfaces; even blades, which it adds to it's claws. As before, it can snip a polyp off and have it travel with other units, this time adhering it to them with it's foamy armor paste. The armoring resin spray produced by the polyps generally isn't as easy for the other units to manipulate, though. The resin spray also has a metalic sheen to it, giving the impression that the Ironclad Crabs are literally clad in iron. Furthermore, it's insulating against heat, especially in thick spongy layers with hardened airless layers to prevent liquids from seeping into the sponge layers.
Besides it's use as armor, the Ironclad Crab can also manipulate the spray to bind to itself and form objects or structures, ranging from long poles to reinforce tunnels, to shovels, to domes for shelter above the surface, or even boats, though the time it takes to do so can vary depending on how complex and how large the created object is.
These are just ideas for now, I almost think the Granroze Wyrm would fit the role that the turbo rozer was designed for better - but the reason Tric gave for not wanting to do it any more is it's large size. I'm not so sure that's a bad thing if we can get under the crater and it turns out to be safe there, but it's just so hard to tell.