When is it time to replace the lipo?

Not how much the battery is bloated. It seems some batteries bloat more than others while still performing ok and it also depends how hard we used them. I have not seen anyone advising to throw away a battery just because it is bloated.

Observed symptoms when balance charging:

• When a 2S doesn't reach 8.4v, a 3S 12.6v, and ends up for eg 8.2v.
• When the difference between cells on a fully charged battery is almost 0.1v
• When a full balance-charge for a depleted battery is only half the battery's stated capacity.
• When the balance-charger times out at 120mins.

Observed symptoms when flying:

• When you observed that you have barely enough power for level flight near the end of each flight and yet the depleted battery reads 7.4-7.6v for a 2s.
• When you observed that the power model loses impetus suddenly on 2 consecutive occassions.