The use of xlpe insulated power cable has become standard in many high power voltage applications today. Its introduction about fifty years ago meant that the previous type of flex were seen as redundant and have been superseded. There have been further developments in both production techniques and materials used in the intervening time.
This means that if you buy xlpe insulated power cable today it will be a better quality cable and will last much longer than the first batch of cables. The main area of development has been is the eradication of moisture from within the cables. The insulation is continuous which means that it is almost impossible for water to reach the wire. You can click steel wire armored power cable for more related information.
The newer types of xlpe insulated power cable need to be laid and connected with care to ensure that all the benefits gained in the manufacturing processes are not lost through careless installation. The high voltages involved usually means that the electricians doing the work will be properly trained and cognizant of the risks in damaging the cable.
Another improvement in today cables is the performance in extreme temperatures. Using both traditional materials such as rubber plus newer compounds has improved the stability and reliability of these cables.
A third factor is how long is needed for a single run of cable. Not all cables have the same ability to be made in one piece. So you need to look at your project and plan for joins and junctions for the cable.