I was considering the XL16i and XR15 when I noticed a model called the XR16. As near as I can tell the XR16 and the XL16i are, in fact, identical with the only difference being that that XL16i comes in a fancier case. Can anyone confirm that this is the case? Dealer just said that yep, that's the case.

I have read some older posts saying that the XL16i is maybe not the best Trane unit with specific complaints being that 1) the difference between the two stages is not enough to be very compelling, 2) the unit is more complex than the XR15 (thus more prone to breakage) and 3) the unit does not do a very good job at humidity control. For #3 I think I read that it doesn't play well with the Honeywell IAQ which sounds like the one to get for humidity control.

Anyone know if those objections still hold tru? I'm installing in St. Louis and will be installing around 8 tons of heating/cooling for a 3700sqft home. Yes, we've done several manual Js and Manual D's so the system should be sized right.

I think the 16i (18-ish SEER) will cost something like $1500 more to install versus the XR15 (15 SEER). I'm not sure what the payback would be for going ~15 SEER to ~18 SEER but a rough look at some numbers suggested it might be around five years. Anyone care to comment?