Question : what are the advantages of using FatPipe technology as opposed to implementing a bonded T-1 solution?

What are the advantages of using FatPipe technology as opposed to implementing a bonded T-1 solution?

Answer : what are the advantages of using FatPipe technology as opposed to implementing a bonded T-1 solution?

That says most of it. The primary advantage of the FatPipes is that can utilize links from diverse ISP's without the hassle or expense of BGP. It is a purpose-built device designed ground up just for that.
If you're getting 2xT1 from the same ISP, then by all means take advantage of the ability to bond them using MLPPP and save the expense of buying/maintaining a separate appliance.