cast iron vs. plastic headers in heater, digital vs. non-digital

[vinouspleasure]

Hi,

we are replacing our pool heater this year. I have found this heater that looks pretty good for the price:
Raypak Millivolt 399,000 BTU Propane Gas Pool Heater - 0-2,000' Elevation - P-R406A-MP-C

from this company:
http://www.poolsupplyworld.com/pools...cts/009203.htm

we have a new pool guy that so far we like more than our last. We live in the northeast and he has suggested 1) this is a good price for this heater 2) we'd be better served with a heater that offers cast iron rather than plastic headers and 3) stay away from digital units due to the high price of repair (our last heater was ruined by mice nesting in the heater in the winter).

any thoughts on his assertions? Would also be interested in any other suggestions or specific heater recommendations.

actually, here's one for $500 more that has glass lined cast iron headers:
http://www.poolsupplyworld.com/pools...cts/009247.htm

worth the price difference? Perhaps the difference in repair cost and efficiency would pay for the higher price?

best,