Oh I'm going to curse you out! Not really, it's all good.
Yes, but there is error in SD calcs as well. Which one has less? Don't know the GM engineer that made the decision to go MAF how could potentially answer that. I believe Pratt and Miller still uses MAF's in the C6R and I'm sure they're more than capable of doing an SD tune. With that being said, I may go SD if I go turbo.
But that is neither hither nor thither. I think we'll just have to agree to disagree...
As far as base tune goes, I highly doubt Holley has a program as well thought out as GM's (keep in mind, still talking only LSx here). Also, all good closed loop computers adjust to driving conditions and are 'self tuning'. How well, depends on how well the base tune was done.
Now let's talk off base tune and into upgrades. This is where I do agree the Holley catches up in cost. After the stock ECU, engine harness I still have to buy tuning software (which had data logging internal). I'm not positive on this, but I believe both efilive and hp tuners have wideband O2 readings in the data. In fact, I'm pretty sure all closed loop ECU's require that to close the loop (thinking out loud). Feel free to correct me if I'm wrong.
So to tally, I would need a stock ECU (~$250), stock harness (~$200), parts to convert to stand alone harness assuming this is going in a C3 (~$100), hp tuners (~$500) and a wideband O2 gauge just in case the above isn't true (~$200) = ~$1,250. So, like we agreed, it is close.
The final area is tune-ability. Now this is tough and a judgment call. I've heard great and terrible things about all UI's in different tuning programs. Don't know what holley is like, nor efilive or hp tuners. I know hp tuners and efilive are extensive with what you can tweak. Not sure about holley. Also, I do like how holley can act as a boost controller. That's fancy.
If I had to buy all of those parts separate and I didn't loose any tune-ability, I would seriously consider holley, but mine came with my drop out Ls1/T56. In the long run, it's all what you get the warm and fuzzy thinking about.