A few things…
first, the image itself says what the numbers are. HP/s and EHP/s.
Secondly, my 3 rules for EVE: 1) don’t mix guns, 2) don’t mix tanks 3) whoever controls the range wins. Rule 2 applies here. If you’re in an active tank situation (shield boosters) then your passive regen is irrelevant, don’t fit for it, don’t even waste any thought on it. There are lots of good reasons for this, but for now just take it for granted that the exceptions to this rule involve some fairly advanced tactics.
That number for your passive regen is somewhat misleading. The recharge time stat from the show-info window is the time it takes for your shields to go from 0% to 100%. So the recharge rate stat is derivative (and wasn’t always even available in the client.) TotalHP / RechargeTime = RechargeRate. Sort of. Except cap and shield recharge rate isn’t linear. The fastest rate is at about 60% HP and lowest closer to 100% and 0%. If you play around with passive shield tank loadouts, you’ll find that as soon as your HP drops below that 60%ish range, your tank is probably broken and you probably won’t survive (unless you can quickly reduce some incoming DPS.)
The reddit reply sort of touches on the idea that EHP is also kind of a lie. When CCP added it into the client, they had to use more generic math than the existing player-made tools could use. With other tools you could put in specific damage profiles based on who you expect to be up against so you’d know how well your tank would hold against specific enemies. When EHP was added to the client, they went off the assumption that you can’t know what you’ll be up against making the number only especially useful when you’re going up against all 4 damage types at once, which almost never happens.