[...] air/oxygen burning temperatures (measured in degF) for different gasses were approximately the following:
Propane 2000/3000
Map Pro was 2200/3200
MAPP 3500/4500
Acetylene 4200/5200
Wikipedia states 2925 °C (5300 °F) in oxygen for the original MAPP, vs. (3160 °C, 5720 °F) for Acetylene. This puts the original MAPP temperature at around 92% of acetylene. Your table puts the new MAPP at about 86% of acetylene temperature, so the new MAPP isn't as good, but obviously a lot better than propane...
Do they also have an in-air burning comparison for original MAPP gas and acetalene? I'm mostly interested in MAPP for what I remember (from reading years ago online) was its incredibly high in-air burn temperature. This was something like 3500 degF. And that is hotter than the melting point of iron, which has a melting point of about 3000 degF. And guess what, if it's hot enough to melt iron, it's hot enough to weld (which by definition means melting the edges of two pieces of iron together so that they form a single piece of iron after cooling). So if you want a good gas that has an in-air (no oxygen tank required) welding capability, then you want the original MAPP gas. Not Map Pro, and probably not the BlueFire replacement for MAPP (unless theirs actually does have an in-air flame temp of 3500 degF). MAPP also is nice in that it's safe compared to acetalene. Acetalene has two ways of responding to heat, the first is burning (reacting with oxygen), and the other is explosive decomposition. The second of these 2 reactions is where instead of combining with something, it breaks down into smaller molecules, and releasing a lot of heat in the process. It's this second reaction that's the very dangerous one, because the reaction travels at super sonic speeds through the gas (far faster than the speed of the flame front travels through the gas when just burning the gas), making it literally a DETONATION type reaction. Unlike the burning reaction, the explosive decomposition, due to it being a supersonic detonation, will generate a shockwave that will tear things apart, just like the explosion of a stick of dynamite.
Now MAPP gas did NOT have that danger. It didn't have explosive decomposition, as a possible reaction. MAPP gas, like propane, only BURNED, so no possible detonation. Yet unlike propane, MAPP gas burned hot enough to weld iron without an oxygen tank (using only the surrounding air as the source of oxygen). The only two known gasses in existence, which are capable of welding iron with only air for the oxygen source are acetalene, and the original MAPP gas (the one sold by Bernzomatic). An accedental leak of MAPP gas (like propane) will create a fire hazard, as once the cloud of leaked gas reaches an ignition source (someone turns on a light switch and the tiny spark in the switch ignites it) will create a flame that travels through the gas, but only at subsonic speeds, burning up your house. There's a chance to survive with severe burns. However, a similar leak and ignition of acetalene gas will trigger a detonation that will blow your house apart, and you too. You'll never be found in one piece again. That's why acetalene is SO DANGEROUS, and something that should be AVOIDED by amateur/hobby welders.
What about arc welding as a way to do small welding projects? That has the added requirement of buying a much more expensive welding goggles than are needed for gas welding (light is much brighter than with gas welding, and generates not only more intense visible light, but also large amounts UV light unlike with gas welding), and needs a power source other than a standard household outlet. Unless your house is fitted with a high current outlet (at least 20 amps) to power the arc welding machine, you will need a separate generator to provide the 20 amps to power your welding machine. That's a HUGE investment. Generators with this much output can easily cost over $1000. And then you need to find a way to safely store gasoline for your generator, and while it's in use you'll also need to provide adequate ventilation for all the CO gas that comes out of its exhaust (to avoid dying of CO poisoning). And that's the other thing, CO is produced at a much greater rate with a gasoline powered generator than the burning of small quantities of MAPP gas from a handheld MAPP gas torch. For small projects that don't involve using the torch for extended periods of time, a MAPP gas torch can be safely used in an INDOORS work area, without risk of dying from CO poisoning.
Really, there is no substitute for the ORIGINAL MAPP gas made by Bernzomatic. It had ALL the properties needed for small, safe, at home, welding projects. NONE of the other solutions have this unique set of features.