[meteoestarreja]

Thanks for asking. This is a relevant question.

The main reason is the stability and sensivity of the receiver module.
Attempting to use the receiver that comes with FS1000 transmitter module, has been the cause of problems for some people. It may work in some situations, but you always lost lots of data packets.
I strongly do not recommend using that receiver.

Indeed no one should use that receiver at least for this purpose.
That was my first receiver (and first error) in early tests and soon realize that I made a terrible choice.
The receiver does work but with a couple of flaws and most of the time it didn't receive the data. Personally I think that you can't even compare both products, the sensitivity is much worse and the noise/gain relation isn't that good. The receiver is good enough for remote control in smaller projects but isn't good enough for getting the station packets at the demanded rate.
I was monitoring all the time during the tests and even a slight change in antenna direction afected the reception (the transmitter was very close so it wasn't a distance problem) and became a reason for not receiving the packets.
So, my advise is if you get both the receiver and transmitter for a low price (last time i bought 2 pairs of tx and rx for less than 2 USD), get it and take the receiver away for other purposes.
The suggested receiver is more expensive but worth the difference