XPL4700 or HRL12390W?

Both are 100 Ah and both weigh 72.73 lbs, so the decision is not about capacity or handling. The XPL delivers 438 watts per cell at 15 minutes against the HRL's 414, carries 2.86 milliohms against 3.00, and holds a 5 year CSB term against 4. The HRL case is 1.35 inches shorter at 12.15 against 13.50, which occasionally decides it. If the shelf takes either, the XPL is the stronger specification.

What does the 4700 in the name refer to?

The block's nominal output at the 5 minute rate. Six cells at 758 watts each come to 4,549 watts, which CSB rounds to 4700. The badge sits about 3 percent above the measurement, and every model in the range is nominal in the same direction, so a worksheet built on model numbers will slightly over-estimate the string. Size from the per-cell figure at your required duration.

Can I mix XPL and HRL blocks in one string?

No, and we will say so before taking the order. The two lines have different internal resistance and different discharge characteristics, so a mixed string is governed by its weakest section and charges unevenly. If you are replacing part of an HRL bank, either finish the bank in HRL or replace the whole string in XPL. A part-replacement that saves money this year usually costs a full string next year.

How does it behave above 25 degrees?

Design life is quoted at a 25°C (77°F) nominal, and every degree above that shortens it. Discharge is rated from -15°C to 50°C, so the block will work in a warm room, but the ten year figure assumes the nominal. Tell us your actual ambient and a specialist will say what it does to the replacement interval before you commit.