1D4 long exposure performance?

hey everyone, ive found a 1d4 in great condition for a fair price and im about to purchase.

but before i do buy, does anyone have any info on how the 1d4 performs in terms of long exposures (300-900 seconds)?

in the past i have had excellent results using a 5d mkll, even with the long exposure noise reduction turned off i was happy with the results

thank you for your time and feed back