[Goran]

Some Porsches already get LiFePo4 starter batteries as standard.
In my opinion LiFePo4 with a battery management circuit is much more suited as a starter battery than any previous battery technologies. After all a starter motor is almost like a mini EV motor, it draws a large current to drive a heavy load. I don't see any EVs going back to Lead acid (be it AGM or not), NiCd or NiMh.

With a low voltage cut-off circuit it should theoretically never be damaged by over discharging.
If the cell management circuit lasts, once you pay the first-time higher cost of a battery with a management circuit, when the cells eventually become useless you can replace just the cells with another set of cells for probably around the same price as a Lead Acid starter battery. I think I saw A123 Systems 20Ah prismatic cells for £25 each, and you only need 4 cells. These are good quality cells not the cheap stuff.

Here's mine, around 30Ah, installed in December I think, so far I'm very happy with it. It hasn't gone into low-voltage cutoff yet even sitting for 7 days. The car really likes the higher voltage of the battery, much nicer starting. I just need to install a proper bracket to hold it down, I'm risking stressing the cables at the moment. The smaller cables taped off, in the background, are the remenants of windscreen heating, I haven't got round to removing them completely.
I bought it from the States, no problem air-shipping at that time, but laws may have changed now.