I know we have tons of A5 threads, but I wanted to share my thoughts and experiences and throw out a poll on the topic. My eyes gloss over when the same three or four guys start talking mechanical tech stuff in every A5 thread, its just beyond my comprehension so that probably plays a factor. Regardless, this is where I'm at currently.

Pros:
1. Increased reliability, decreased parts wear, and maybe recoil mitigation - though it is VERY debatable how much of a real/perceived benefit any of this is for the vast majority of shooters
2. Increased tune-ability based on available buffer weights

Cons:
1. Shit availability - if you're able to find everything in stock, its rarely all in the same place. The VLTOR tube doesn't have as many positions as the BCM or Magpul, so the latter are preferred. However, BCM's kit only comes with an A5-0, which is weird and somewhat pointless. The Springco Green SPring is also typically regarded as better, and again, is not sold in any kit that I'm aware of. On a good day, I'm ordering a buffer and tube from one place and the Springco from another. I'm pretty sure I've had to buy all three from separate vendors before. Then you add the castle nut and end plate, its just obnoxious.
2. Cost - piecing together all of the separate parts is probably around $125, at best. The BCM mil-spec kit is $57.95.
3. Extended OAL - not really a big deal in use, but my ARs are just barely too long to fit in the foam inside of my hard case, because of the A5.
4. Factory lower options - there are plenty of reasons for building your own lower, and I swap most stuff out of a standard LPK anyways. However, there are very few factory options with the A5 already installed and at least the BCM, from what I've seen, only comes with black furniture and a non-SOPMOD stock. I think there re even fewer complete rifles with them.
6. Proprietary parts - I'm all for spare parts, but if somehow you get caught with your pants down, most LGS will probably have standard carbine buffer parts on hand. Maybe they'll have a rifle tube and spring, but the buffers themselves stay pretty scarce.

Bottom line, with few people shooting FA and a growing demand for minimalist gas port sizes, I just don't see the increased performance as being worth it. Again, this has just been my experience. I haven't removed my current two yet, so if I'm way off base on the pros side, I'm up for some knowledge, but I think the vast majority of solid-perofring guns out there use the standard system so I'm not sure tht there is anything that could be too convincing.