I have found reading both the GNT and the LXX an incredible help to understanding God's word better. Here's just one example:
I noticed the other day that in the letters to the 7 churches in Revelation, the opening line for each letter is:
ταδε λεγει followed by a description of Jesus
This can be seen in Rev 2:1, 8, 12, 18, 3:1, 3:7, 3:14.
In English translations this is translated as:
ESV "The words of him..."
NAS "...says this,"
NIV "These are the words of him ..."
NET "This is the solemn pronouncement of the one ..."
Now, a few days later when I was reading Isaiah, I saw this same phrase,
ταδε λεγει κυριος "Thus says the Lord." Isa 38:1.
I realised that I had read this a few days earlier in Revelation, I went back to Revelation and realised that all those ταδε λεγει's could be translated as "Thus says the one..." which is very similar to "Thus says the Lord".
I then did a search for this phrase in Bibleworks, and saw that Agabus used this phrase in Acts 21:11
ταδε λεγει το πνευμα το αγιον "Thus says the Holy Spirit."
This was very interesting to me because I have been reading various books on prophecy recently. Some claim New Testament prophecy is different to Old Testament prophecy, some claim it isn't. I don't think that my little discovery here ends the debate (and I'm sure I am not the first person to see this!), but it does show a certain amount of continuity between OT prophecy and NT prophecy.
The impression I get is that when Agabus prophecied, he believed he was speaking God's words, much like an Old Testament prophet.
So, all this to say, that it was by regularly reading a Greek New Testament and a Greek Old Testament that I was able to stumble across this. Nothing ground-breaking, but it does show one of the benefits of using your GNT for your devotions.