So just played this today as a Synthetic, and I 100% disagree with the suggestion. The single coolest thing about the Synthetic is that they can do crazy shit in terrible situations without concern. It really separates them from their human counterparts. Overload is amazing and isn't something that you should penalize.
Since Overload ? Stress, it was great to think about Overload as 5 "awesome points" that can't - or at the least require significant time and/or expertise - be healed in the field. We didn't have opportunity to perform repairs of any kind. So they become this precious resource, that you want to nurse to do crazy inhuman stuff or get out of an awful roll pinch.
So for example, after an amazing Assess, I perceived that one of our troops was about to take a grenade based on the sound of the opposing forces. I used two overload points to meet the grenade, and another to catch it and toss it back. And another for deftly dispatching the most dangerous threat to my squads life in another scenario where we were at a big tactical disadvantage.
Later I was torn in half by dog-xenos in a very unfortunate set of rolls. As "Private Hoggie" was attempting to rescue my upper torso, a humanoid xenomorph decided to crush us from above, so I used another point shove to him away and take the full attack (Preserve Human Life as my Directive). That felt super awesome and appropriate for the character. And as I was already so damaged and (would be) stressed at that moment, it wouldn't have been possible with the suggestion above.
Since this is a general thread about Synthetics, I'll add a few other notes:
The game is very Aliens and not-so-much Alien in that you made Synthetic a class and not necessarily hidden information. So you can't be a Synthetic Medic/Scientist a.l.a. Ash. You can only really be some flavor of Bishop. The Synthetic class seems like it could be reworked into a general Scientist class that could be human.
I think it'd be cool to allow any class to be Synthetic (with the option of that knowledge being hidden), with a set of Synth options that could apply to any character at the expense of other human benefits/risks. A little tricky to work out layout-wise, but it would definitely add an interesting layer.
The Synthetic seems to be able to take the game in a more Alien direction with it's "science-y" moves if you wanna play up the, "what the hell is going on in place" and delay the run-and-gun a bit, so by decoupling the science stuff from the Synthetic I think that could be really helpful.
Going in, I didn't know how much action I was going to be in for a first game so, I picked 'Designed to assist' over 'Combat model'. As it turned out, I had a few opportunities to be helpful, but in the end I was most effective as a damage sponge. Had I really wanted to fight it would have been tough. In a very action-y interpretation, which the game is definitely inclined towards considering the default scenario and the balance of the rule text, overload and combat model seem almost essential.
Regardless, I love playing a Synth to death, so I might take some time to hack at this.