I have Brenton's text as well, though note that Brenton relies almost exclusively on the B text (vaticanus). It's not really a critical text. Most of the time I'll use my mini-rahlfs, that little guy published by the bible society. It is more of a critical text, but not completely. For anything serious I'll stop by the library and consult the big mother multi-volume kittel edition, though there is a new full critical text in the works, teh name of which I forget at the moment.
Funny story, once I got in trouble in a class because I was arguing based on this or that LXX text, which I had taken from Brenton. The prof was mystified because his LXX, mini-rahlf, had no such reading. This was early on, before I knew anything about manuscript variations or critical editions or anything. To solve the mystery I brought in my Brenton to show my prof and he opened the cover and laughed at me; see, I had always called him Brenton, I never noticed his first name, but this prof did, and laughing he said "here's your problem, any edition published by a guy named Sir Lancelot!!"
As for the OP, have fun with your septuagint. I found LXX Greek much easier to read after I got Hebrew under my belt. Prior to that the LXX always seemed freaked out, but then I realised that it is kinda just Greek with Hebrew word order, almost.