I'm still running a 1660 with 4450 hours so, yes we do keep them.  The way I'm looking at them is, what will $100K or 150K buy me.  Around here to get less than 2000 hours I'll get a 23 or 2588 and I can't find any for my price that haven't been in rice.  2188's will be more like 3500 engine hours.  I can find 1500 engine hour yellow's that have been in grain for that money.

Downside is I'll have to trade heads, mine are just too small for a much larger machine.  I could get by with the same heads on an 88 series red machine.