Allow me to add a fourth.  I did something very similar to this in my last campaign in an attempt to "Humanize" the aggendi.  (no one wants to have a romantic subplot with a 7 foot slavering lizard).  Here's the deal. In 1521, Lord Dremmond uncovered some ancient genetic research on the aggendi in the computers of asteroid Karmuria.  In his bungled atempts to replicate some of the experiments, he created a being half Human, half aggendi.  The first attempt was killed shortly after birth (remember the thing he impregnated Arnellia with in Rimfire?).
        Later experiments, using kidnapped women as incubators (who usually didn't survive the birth), yielded better results.

The Hybrids (sorry, but I can't bring myself to call them Huggendi.   It sounds like a Care Bear) are weaker than full aggendi, but in many ways more dangerous.  They are far stronger than an average Human, and display more initiative and motivation than the aggendi in the absence of the massmind.  In addition, as a side effect of the gene splice, they have a very unstable genetic structure, allowing them to shift at will between a full aggendi and a fully Human form.  Their "natural" form, which they assume when unconscious or distracted, is largely Human, but with pale green, leathery skin, solid yellow eyes, and sharp nails and teeth.   The instability also causes them to dissolve into a puddle of goo when killed.   They mature quickly, heal quicky from almost any non-fatal wound, and have a phenomenally long estimated life span. As if that weren't enough, the existing aggendi biomecha will accept commands from them as if they were full aggendi.

Since Dremmond's demise, they have been the primary antagonist for my campaign.  Most just want to live in peaceful obscurity, but a few bad apples are convinced they can return the aggendi to their former glory.  Fortunately, there are very few of them.  The knowledge of how to engineer more died with Dremmond.   The aggendi have no gender, being a cloned race,  and while the Hybrids have males and females, their aggendi heritage makes them all sterile.

(Interestingly, Dremmond engineered one Hybrid from an aggendi and a captured Elomani female.  Along with being naturally telepathic, the Hybrid was actually fertile.  Unfortunately, the child was shot dead by a PC before she reached puberty, and the other Hybrids are still pretty pissed about it.)

They are built as Human characters, with the following modifiers:
(mind you, these are for fuzion, but can easily be adapted to zeta)

They also have the following special abilities:

• Metamorphic: Hybrids can switch at will between natural form, Human, and aggendi.
• Rapid Healing: Recovery times are halved in all forms.
• Longevity: They mature in 5-6 years, then age at 1/10 Human rate thereafter.
• Natural Weaponry: Claws do [STR-2]D6 hits in natural form, [STR]D6 in aggendi form.
• Natural Armor: SP 5 in natural form, SP 10 in aggendi form. Cumulative with worn armor.
• Limited Telepathy:   Like full aggendi, the Hybrids can transmit their thoughts to other Hybrids or aggendi within a range of a dozen meters or so.  This is not full telepathy, and is not a complete mindlink.  The connection can only send and recieve images and ideas.
• Massmind Abilities: Of course, in 1530, the massmind is long gone, but IF it were to return, the Hybrids could access it.  The only difference is that they take a bit longer to link up, and retain no connection when not linked.
          Note: full aggendi, even when not linked, can be detected by the massmind, and it knows what they know.  Also, the Hybrids, unlike full aggendi, can chose not to follow the massmind's directives.   They are much more independent thinkers than full aggendi.

Obviously, this is pretty unbalancing for use as a player character race.

However, I have an NPC Hybrid, named Mina, in the PCs mecha squadron.  She was raised by Humans.  She is a competent pilot, but very naive.   While physically an adult, she is chronologically seven years old.  Hybrids are fast learners, so she has a comparable adult education, but the emotional development of a seven year old.  Mina has been a LOT of fun to play, especially before the players knew what she was.  (Picture a skinny teenage girl tossing a Kargan marine around the gym like a rag doll, apologizing sweetly each time she helps him up).  One PC is even dating her. They make a great secret enemy too.  Almost as tough as an aggendi, but more clever, and able to blend into any crowd.  Kill one and it turns to goo, so they are difficult to study (or even prove they exist).  The truth is out there.