Why so tense?

Way back in December of 2007 I was translating John 1:4 on this blog, using the Tischendorf (1879) version of the Greek text from http://www.greattreasures.org, and noted that in this version the tense of the verb εἰμί (I am) is present indicative, while the UBS and it seems most other versions use the imperfect indicative.
You can view my parsing and translating from 2007 here:
http://www.winebrennergreekstudygroup.blogspot.com/2007/12/john-14.html

But what does it matter? Why is the tense important?

This is the exciting thing about Greek Grammar to me. It matters because this is God's word and we want to be faithful to express it as he meant it, not just in some sloppy haphazard fashion. It is important for us to consider the differences brought about by a change in tense.

We might translate John 1:4, "In him is life and the life was the light of men."

Or we might translate it, "In him was life and the life was the light of men."

The fact that both of these are biblically supported true statements, I think, draws us into a deeper understanding of our Lord and Savior, Jesus Christ.

Is John speaking of the eternal, pre-incarnate, life that has enlightened men for all time, or is John making a statement to those in need of life TODAY who can find it in the source of life, namely this eternal Logos, Jesus? It may seem a fine nuance, but thinking about it causes us to think about Our Lord, who both WAS and IS life and light for each of us and all of us.