User blog comment:Blaisem/Toughness vs. Tough Body/@comment-24659969-20141121181825

You missed one thing about why Tough body is much favored by heavoes (especially those "speed assault" heavy build) It is what I call as fixed heal numbers. While toughness means you have more HP. It only scales healing from medkit (not the medic skill). However Tough body indirectly increase effectiveness of healing factors with fixed numbers instead percentages. These healing factors are HP regen, biosynth, and medic heal which are primary sources of your HP healing on high levels when playing as Heavy because you wont have time to look for that big heal box or hoping one to drop.

For example you have 40 HP regen/sec. With toughness, if you took 1000 damage, thats it you need 25 seconds to heal that. But say if  you have tough body 25, that damage is reducted to 560 which only requires 14 seconds to heal that much.

So much it is wise to say to actually you should level both balanced or even (nearly) maxed both if you dont want to reset and fine on every equipment you use. Example 13 toughness and 13 tough body.