What i expect is a systtem that doesnt devolve the game into an eercise of weights and measures. Encumbrance systems like this are tedious. I don't play 40k games for tedium, there's plenty of that in real life. All you need is a simple soluution or the apllication of common sense: you can carry a couple of pistols, or a rifle, but you can' carry rifles, pistols, carbines, and a massive cannon. It's not really rocket science!
Well seeing as it only devolves into that if you bother with worrying about those rules then you'll be fine there.