Light hydrocarbons are all release around 20,000 BTU/pound of fuel when burned. It varies +/- 5% depending mostly on the Hydrocarbon:Carbon ratio. Hydrogen is much lighter than Carbon so propane (C3H8) has more energy per pound than butane (C4H10). Propylene (C3H6) is as low as the Hydrogen:Carbon ratio can go at 1:1 so that is not as good (by 5-10% x whatever its fraction of the mix is).
OTEPOH (on the ever-present other hand), we don't haul around methane, ethane or pure propane for their higher heat contents (due to that higher H:C ratio) because their higher vapor pressures requires a much heavier container (usually, unfortunately, made of steel).
AYOTTH (and yet, on the third hand), a modest percentage of those higher-vapor-pressure gases (usually iso-butane or propane in a backpacking canister) help operation in cold temperatures. Slightly more steel is needed in the container, but the canisters are useable to a lower temperature without invoking quite as many tricks (immersion in warm water, putting a tea candle under the canister, using copper wire or a copper strip to conduct heat from the flame, etc).
I'm intrigued that it is marketed for "brazing" which requires a higher temperature than the more common use of portable torches – soldering. There are several gases (BernzOmatic's MAP* gas, "Flame temperature in air of 3,730° F, ideal for medium to heavy soldering and brazing") that burn hotter than propane ("flame temperature in air of 3,600° F"). I suspect the propylene is in the mix to boost the flame temperature because brazing is at the upper end of what you can do without using an oxygen tank as well.
*Methyacetylene**-Propadiene
Methyacetylene=Propyne and Propadiene are each C3H4 so they are between propane and propylene.
Here's some data on different fuel gas canisters (not BPing canisters, but for torches):
http://www.bernzomatic.com/products/fuel-cylinders/
In general, a higher flame temperature makes for better heat transfer to the pot. That's good. Unless you've got a marginal design like some JetBoil pots whose heat exchanger fins can be damaged by high heat. Also (and this is an advanced concept), when you get into HX pots or melting snow, you get some condensation of water vapor from the flame exhaust and that transfers a fair bit more heat. This loops back to that H:C ratio – more H makes for a lighter fuel and more H makes more water vapor which can release its heat of vaporization back to the pot – something that the CO2 from C never does.
In summary: Seems totally fine as a BPing fuel. If it is better in any way, it is only 5%-ish better, but I suspect the low H:C ratio and the long (less spherical) geometry of the canister outweigh any advantages from higher flame temperature or (possibly) a better vapor pressure. Best guess: 400 grams of this (fuel + container) will boil as much water as 375 grams of any modern BPing canister + fuel. Also, once you move beyond the mass-marketed propane cylinders, I've found the speciality-gas cylinders for brazing to cost a few dollars more each.
