Thanks for the vote of confidence,
The Gaunt formations do look fragile, admittedly.
But if I was to follow the advice, I would have to drop other interesting stuff like Dactylis and Barbed Heirodules, as I would simply not have enough Uncommon Brood slots to take them- it's a complex balancing act to write a Nid list and keep within all the various limits, I'm not sure if it's very good or very bad that this is so.
It's also a tough choice to have more Synapse + protection in a bigger formation, but have less Activations. My list is already quite poor for activation count.
I don't hold much confidence in the Gaunt formations, my experience has shown them to be poor and fragile, admittedly my experience has been vs. Eldar, but against most other opponents, the sheer casualties they take and the usual fact I'm being engaged by the opponent rather then the reverse (due to their speed and SR) usually puts it firmly in the opponents favour.
I aim to use these Gaunt formations to 'quietly' take objectives, and sometimes provide supporting fire. Hopefully if the opponent is aiming AT fire at them, it's not going towards Dominatrix, Heirophants or the Harridan- the real players.
My experience vs Eldar has permanently put me off Close Combat only units, it was just simply embarassing not being able to hurt my opponent with nearly half of my army. An entire Genestealer formation just with their thumbs up their butts cowering from skimmers. Same with Lictors.