I have ordered from hasslefree (those rifles that are basically straight from the aliens film) and that size stuff works well... with 1/35 i think it does look alright on imperial guard models but they are a realistic size, so the minute you mix in a normal
40k weapon they look tiny, flimsy even.
I would advise stuff from
http://www.theassaultgroup.com/ they do some great weapon and equipment packs and they are just a little more 'chunky' then 1/35 stuff so i think it fits in better alongside conventional
40k models.