Which rulebook are you using?

I hate lugging round kilos of books, but I despise phone apps more!
Since 9th dropped, I have left my hardback rulebook at home and taken my GT2020 to friends' houses and clubs, playing missions and Secondaries from the GT.
(I take my codex too, and lament the fact there isn't an A5 softback version!)

Recently a friend objected, as he strictly plays from the hardback book, and felt I was gaming to advantage by taking a secondary with which he wasn't familiar. I accept that from his point of view, it could be perceived that way, even if it wasn't my intention.

Now we also have FAQs, and GT2021.
We also play Codex:Drukhari, but might bring expansions like The Book Of Rust.

From now on I will make sure the choice of rulebooks and codices gets discussed in the pre-pre-game planning stage, but out of interest, what's your preference?

You are 100% in the right. If you are playing "Warhammer 40k", the assumption would be with the latest rules. If someone showed up with their 7th edition codex and rulebook, I would have an issue with that (unless it was specifically discussed before the match).

Going to attend my first tournament in a few months, my plan is to make a small binder with all the relivent rules. Photocopies of everything, my back still has not healed from lugging around 20 lbs of books when I played Guard back in 8th XD

I'll just echo that that base assumption is that the latest rules should be used. If someone for whatever reason want to use old outdated rules they should say so beforehand.

If I was going to an event I'd probably do the same as fisheyes,just make a binder of printed rules because the books are horribly inefficent for actually looking things up and with how many different things you need now it's much simpler to just have all the relevant things in one binder instead of multiple different books and printouts.

To be honest, your friend is completely unreasonable. You're playing with official rules.

Using his logic, you shouldn't be allowed to use your codex secondaries either since he's not familiar with them. The fact that he's not familiar, is NOT your problem. The GT rules are specifically designed to be the rules you carry with you when you travel and play.

To answer your specific question here, I also use the smaller rules book when I travel, for all the same reasons you highlight. We have enough heavy paper to carry around with us as it is.

I tend to carry the GT book over the 2-tonne hardback copy - as I also have the Drukhari and FW books to carry with my current list, the less I can carry the better.

And I agree with @Silverglade - that guy is being ridiculous.

Thanks all. I wouldn't go so far as to say ridiculous, as the current BRB (with relevant Errata updates) is a valid form of the rules; GT2020, and GT2021, are variants on those rules, falling somewhere between optional expansions, rules updates, and an alternate universe!

I am happy that I am not wrong, but I also feel that he isn't wrong either, from relative points of view; this is the problem with having multiple alternate (and expensive DLC) versions!

Things would be so much easier if they would just print Players' versions of the main rulebook, without all the fluff and pictures!