I'm not sure how well the HiVi M10 performs but I'm sure Edifier C3 and HCS2330 is a little to sharp for metal

since you are talking bout heavy metal I assume the drummers are crazy with cymbals so C3 can get annoying and painful at times but taming down the treble would do
Gaming on C3 is good though. Full bodied sounding with good throbbing bass if placed properly
The HCS2330 will not do well in metal as it's a little dry
you can try out the Edifier 2.0 series though

The Edifier R2000T seemed to work pretty well with speed
Edifier R2600 is quite interesting in sounds and able to produce guitar distortion properly without turning into noise (if my memory is still correct)

it's really up to preference when it's about speakers with subwoofers

I personally do not need a subwoofer unless I'm gaming or watching some serious action movies (even so I still do not need a subwoofer because my stereo bookshelves are able to do it but it's better to have a separate subwoofer for some helping hands)

and plus subwoofers are meant to be on the floor so it should be fine if you are on a 2.1 setup

Subwoofers are just an extra for boom effects like explosions or deep hard hitting beats of music
usually hip hop,pop,rap, or any electro music needs a subwoofer to give taste to music.

but if a funky rock music with a melodic bassist inside, it's good to have a subwoofer too.

But don't worry as 2.0 setups are capable of producing bass
just that it's unable to produce sub levels that pounds hearts

in return bass in 2.0 are usually smooth flowing and doesn't feel separated since they are all in ear level

Well the 2.0 series I mentioned may be a little too big so............ I hope you can clean up some space for a brand new speakers XD

well haha sorry for assuming that you have messy table   

I guess you need to consider some tables as well
for that budget I assume you can only get the R2000T since the R2600 is RM100+ more than your budget

If you don't fancy bass at all then you can consider some smaller units like Edifier R1600T or Edifier R1900T(suits music more)

other than that you can also consider a different taste such as Altec Lansing VS4621 or Edifier S330D but I wouldn't recommend that due to various reasons as
-VS4621 may feel a bit plastic like
-Edifier S330D had bright trebles that you cannot control

but if you had a chance to test the HiVi M10 do post your impressions about it here

HiVi D1010-IV. RM 399. You can audition the speaker to find out why people love this sub RM 400 speaker so much

You know what, we are considering opening an interest check for HOME AUDITION for the M10 and D1010-IV. These two speakers sound particularly good ONLY in home and on the desk. Often time they are too "small" for any store to properly demonstrate the speaker's true potential.