It'll be beneficial to any speaker, and you might find it more beneficial to budget speakers ore than high end - high end speakers tend to be weighty already, whereas more budget speakers tend to be quite leightweight in comparison, especially larger budget speakers.
It will vary from speaker to speaker as to how much is beneficial, so matengawhat's idea of using 1kg bags is a good one. Not enough and there won't be a big enough difference, too much and they could come across as being too bass heavy. It'll be similar to filling stands - find the perfect amount and you'll get the best from the speaker.
Everything should tighten up, especially the bass as the cabinet is much more stable. Bass will become a little stronger too, due to the drive units being able to work a little more efficiently. You may find other areas benefit too, it's a case of trial and error.
And do make sure you use the bags - unlike the guy who brought his floorstanding Mission's back to the place I worked about 10 years ago because the bass units were making a scraping noise - I opened them up to find sand absolutely everywhere.......