This D3 build sacrifices max shield health for a bit of extra damage. It intentionally does NOT hit the soft skill power cap (125K), instead sitting at ~113K, with shield health reaching 2.2mm instead of 2.5. Practically speaking, there should be no noticeable performance deterioration, especially in a good group composition that includes a Reclaimer. Staying near full health due to heals means burst heals from medkits and/or detonated support stations will keep the shield topped off. I can usually get through legendaries without the shield breaking at all.
Note also, that since you're trying to stay near full health, Unforgiving may not be the best talent choice. I would probably opt for Deadly/Destructive given the option, but as this is the same House I use for my PvP builds, I stay with Unforgiving. Alternatively, I often use the backup MP5, with sustainability skills on it. I'm almost never in danger that way. Those skills ARE predicated on kill shots, but I don't find myself having a difficult time getting them.
The Secondary weapon takes Determined in the free, b/c if I'm using the Secondary, it's b/c my shield is on cooldown, and determined is a good option to get it off. Note, Coolheaded is also a good option here if you are good about hitting head shots. Coolheaded is arguably a better choice, as it doesn't require the killshot to be effective.