Obviously I've only had a chance to look over them as the PTS is only just out but very few of the prestige perks seem on paper to be worth the grind in any meaningful way.

Just a quick query about some of the language used: The prestige perks on Heavy which reference "charged attacks" but have the icon of the space marines foot, suggesting its only the charged melee attack which is affected.  But heavy can also have charged ranged attack on the Plasma weapons, so do these prestige perks apply to charged range attacks?  This is the same on the Bulwark "Overcharge" prestige perk with an icon suggesting its only melee.  

If it only affects melee (charged or otherwise) then it would be helpful if the per description said this.  If it affects both ranged and melee charged attack them it might be useful to say it affects both.

As for the actual perks:

Heavy - Assuming the charged attack perks are only for charged melee attack then I'm really not sure what the goal was here.  The fact that four of the seven prestige perks are potentially about buffing Melee for the class which is supposed to be the big shooty class is a really weird choice.  These perks don't feel like a way of making the class better at what it does, it feels like a way of making it into a different class.  Also the perk "axillary reload" - why in the world would killing an extreamis level enemy or higher in melee (melee again with the shooty class) be worth rewarding a single magazine of secondary ammo?  For starters the heavy needs primary ammo, we want people to be using their big gun its why they are here, secondly why are these perks once again encouraging the shooty class to be a melee class?  It makes sense to have that as an option on the Bulwark and we do, but on the big guns shooty guy?

Tactical - Second look is a great idea!  Its the unique to the class and most importantly it encourages the player to actually use the skill more, I want to take this type of perk!  However prestige perks with "Below health %" thresholds are not exactly something I want to aim to use.  I don't want my character sitting at less than 25% health to be benefitting from a slightly faster charge rate on my scans, I want my guy to be at as high health as possible for as long as possible.  When i get down to lower health levels my concern is how to i raise my health pool back up (thats why the Resilience prestige perk might be pretty good as that will give me about 50% health back on stim use), i'm not going to pick a perk which rewards me for being below a health threshold instead of a perk which helps me get out of that health mess.

Sniper - four of the sniper prestige perks are for situations where you are probably in melee combat or at least close combat (exacting force, versatility, adrenaline boost, versatile precision).  Now you can build the sniper as a pretty fun melee person using the block knife and some other skills, so ok, this can be workable i guess.  It is however a little jarring when you realise that NONE of the prestige perks make the Sniper class better at sniping.  You know the long range, not melee, shooting bit which the class is named after and designed around - no prestige perks to help it actually snipe stuff.  How does this happen?  What was the plan here?

As for the other classes they seem ... ok? Its just very few of the prestige perks so far seem to be rewarding good play or encouraging smart play.  In truth there seems to be very little synergy between these perks and how the classes actually can be used.  

Rather than perks which only activate when the player is close to death, a position they don't want to be in, why not have perks which are active when the player is above a health threshold and deactivate when they drop below it?  That is one way to encourage and reward smart play, it also means the these types of perk will be active and useful from the moment the player starts an operation.  Additionally the prestige perks should be something which feeds into how each class can play, the heavy's prestige perks should be about using heavy weapons and the things that are related it that like ammo and weapon heat, not perks which "turn the class into a melee powerhouse".

Consider also having within the prestige perks for each class something with a team benefit component.  While playing the game after release i grew to appreciate other classes for how they helped me just by being in the team.  This is a powerful way to get players to want to try other classes and to get them talking about party compositions.  For example lets say once class gets a prestige perk which shares ammo with the group when it pick up an ammo box.  The individual player might get less ammo but if I'm a sniper or a heavy I will love having that guy in my group.  If you want to remove some of the bulwarks banner heal, allow a different class to use medkits in a small AoE around themselves as a prestige perk they select.

Prestige perks have the potential to be powerful but also fun tools for the players.  They can really encourage interplay and cooperation as well as discussion about good groups compositions.  This current list of perks are just really uninspiring.