OK, I have jumped on the Trinity hype train and bought a Trinity Delta V2.
Thank everyone for the advice and thank Midgetguy for telling me about the discount code.
I just received the Delta V2 two hours ago and did some very basic comparison with VSD3S. I'm really a newbie in the audiophile world so please forgive my poor grasp of technical terms.
Sound Quality
With default gun metal filter:
Bass: Bass is noticeably more punchy and has a larger quantity
Mids: Mids seems to sound slightly less "forward", but more "left and right"
Treble: Seems to be less clear/smooth than VSD3S (not too sure)
Soundstage: Instruments are more separated (i.e. in more well-defined layers). It may be related to what I have said for the mids - things sound less forward, but more left and right.
Details: Able to show some more details (e.g. some very light strings at the background) than VSD3S
With silver (damped) filter:
Bass: Overwhelming bass. I would have loved this if I tried this 2 years ago. However, after listening to VSD3S for 2 years, I actually find this too much.
Mids: Very recessed compared to gun metal filter or VSD3S
Interestingly, when I first bought the VSD3S, I didn't find its sound as amazing as people on the Internet claimed to be. (I didn't test it before the purchase). But after 2 years of use, I now like the sound of VSD3S a lot, except for the slightly small bass quantity. Perhaps I just need more time to burn-in the Delta V2 and my ears.
Comfort
Again, when I just bought the VSD3S, I found it quite uncomfortable. It was my first time using an over-the-ear IEM. Yet, after 2 years, I now find VSD3S very comfortable, much more so than the Delta V2. VSD3S can sit securely and naturally in the ear pinna. For Delta V2, if I wear it with cables pointing directly downwards, the sound is easily affected by any movement of the cable. If I wear it using the over-the-ear style, the cables point to a rather odd direction. Besides, you have to manually adjust the cable direction every time you wear it. (Since VSD3S is designed only for over-the-ear wearing, its cables always point towards the correct the direction for over-the-ear wearing).
The long length of the metal shell also seems to be dragging the IEM downwards, causing a little bit discomfort.
Again I may need some time to get used to Delta V2.
Build Quality
The metal shell of the Delta V2 is nice, but I wouldn't necessarily say that a metal shell is always stronger than a plastic shell. The connector between the shell and the cable does not give a clicking sound when connected. It simply becomes tighter. I don't know which design is more durable, the Delta V2 or the old VSD3S, but I guess we can all agree that VSD3S didn't really do well in terms of build quality. Only time will tell if Delta V2 is indeed better.
Accessories
Delta V2 wins by a landslide with its numerous filters, ear tips, mic-equiped cable, mic-clip, L-shaped connector, hard case, etc
Value
Delta V2 is supposed to be much better than VSD3S, but I can't really feel this the moment. I can tell that Delta V2 and VSD3S sound different, but I don't know which one is better. I think I need more time to explore the Delta V2 (just like what I did with the VSD3S). But in any event, I don't think sound quality alone can justify the Delta V2 being almost 3 times more expensive than the VSD3S. I guess a large part of the price is devoted to accessories, free international shipping, labour cost (I assume it's much higher than that in China) and possibly better build quality.
