The LiFePO4 chemistry can take abuse lots.
Whilst they can take more abuse than the regular LCO or LMO chemistry cells, I wouldn't say they can take "lots", nor would I say it is solely to do with the chemistry.
Packaging makes a large difference; cylindrical cells are far more robust than their pouch cell brethren, their metal case provides a far stronger enclosure to the cells, reducing physical damage and removing the need to "clamp" or "squeeze" the packs. Often when referring to cells taking more abuse, people compare across different chemistries and across different packaging somewhat invalidating their claim.
Manufacturer makes a large difference; dodgy, no-name manufacturers may have poorer quality control, less stringent testing, a higher level of acceptable defects. People often compare across different chemistries and manufacturers somewhat invalidating their claims.
Eg; An A123 LFP cylindrical cell vs a Turnigy LMO pouch cell instead of A123 LFP cylindrical vs pouch or a Samsung LCO Cylindrical vs a Ultrafire LCO Cylindrical
You will have a lot more fun minus the SLA batteries weight. And you will learn more about LiFePO4.
I dunno, i think in this application the weight difference will be pretty negligible, his "gokart" uses 2x 7ah 12v in series, they are about 2.1kg. an equivalent replacement with LFP would be 3p8s, if you use A123 26650s, which weigh 74 grams each, that would be 1.776kg vs 4.2kg, or a difference of 2.424kg, not much at all.
And then there is the price... even with price estimates in favor of the A123 cells, it still looks bad, over estimate the price of a pair of 12V7Ah as being $50, and the A123 cells being $110 (about $9 ea).
In this application, I'd say the upgrade value is somewhat dubious.
I repeat though, In this application.