Hasselblad PME 51 vs PME5 - any major differences?

I'm shopping around for a metered prism for my 500cm and I'm deciding between the PME5 and the PME51. I'm leaning towards the PME 51 but aside from being slightly newer than the PME 5, I don't see any real differences between the two. I think I read somewhere that the PME51 has updated electronics, but what those updates are, I have no idea. Is there any good reason to get the 51 over the 5? Or should I save some $$ and get the slightly cheaper/older PME5?

The PME-51 (1994-2000) had improved meter electronics: reduced power consumption and higher precision. (Allegedly)
The PME 5 was not in production very long 1991-1994 the 51 was discontinued around 2000 so more about, twice the years of production.
Interestingly the PME51 was available at the same time as the PME90 (both in my 1997 catalogue) the PME45 coming later in 2000 to replace the PME51, all are three are in the 2000 catalogue with the PME45 noted to be replacing the PME51 that year.

I have the PME. There is not a lot of difference between the PME5, and PME51 approximately six of one and roughly half a dozen of the other.