I bought an Air Venturi 4500 compressor. It worked well for a bit, filling a 15 and 60 minute tank. Then it failed. Air Venturi tried to walk me through some possibilities via email, I bought parts, and attempted self-repair, but it as it turned out, there were several points of failure. I sent it back to them on my dime and they fixed it under warranty. That whole process took months. In that time, I bought a YH off ebay. It failed in the first hour. They took it back, and I got another. It failed in the first week, they took it back, i got another. It's been running well for almost two years now, although since my Air Venturi has been returned, I rarely use the YH. I run Nuvair 455 oil in these compressors, and use ice blocks in the water for the YH...basically, I do everything possible to baby these things, while using them. I have big bores that breath a lot of air, as well as standard caliber guns, and I am lucky to be able to shoot in my backyard....I use air. I fill tanks several times a week on a normal week.
The failures, back and forth shipping (it's a half hour drive each way to get to fedex) time spent learning about compressors, ordering parts, making repairs, etc has not been insignificant over the last few years. In hind sight, I wish I would have just gone with an Alkin. However, when I got in the pcp game, I only had one Marauder, and the idea of spending $1400 dollars on a compressor seemed crazy and was a big expense for my finances. I was a pump and break barrel guy who mostly shot and reloaded for powder burners.
Over the years, things have changed, and I now primarily shoot pcp's, so even at my modest income level an Alkin can be justified. My AV 4500 churns along, but I don't trust it enough to supply air to friends, and I have friends who would like to get into pcp's, but it's tough to do in my area without an air source, and again the closest dive shop is a half hour each way and they're only open in the summer.
So, to answer your question...the AV 4500 is an adequate compressor if you get a good one, as are most Chinese compressors. I would not buy another one, and I don't feel like I got a good value for my money. There is some level of service available, so you're not entirely without recourse if it fails, but shipping price to Ohio from where I live costs almost as much as a YH. When it's running, I like it much more than my YH. It will fill a larger tank in one shot, it's quieter by a lot, and it doesn't require the prep of getting an ice bath ready before operation like the YH. Is it worth $1400...I don't think so. I really thought I was getting a lot more for my money when I jumped in. An Alkin is a little more than twice as much, but for the amount of money I spent on shipping, a back up YH, the hassles with getting a good YH, the parts, and my time (which I highly value), I feel I coulda had an Alkin. However, I would have never spent that kinda money for the one PCP I had at the time.
Another factor to consider is filters. I have another $300 dollars in two filters and the necessary lines to tie it all in: I was not comfortable with just running the air out of the AV 4500 into my tanks, and I certainly wouldn't do that with a YH. It all starts to add up.
PCP's are an addiction. They are also evolving at an amazing rate in terms of performance. Additionally, where I live, they will most likely be highly regulated very soon, and currently they're not, so I have invested. Figure out what works best for your situation based on the feedback you get here. Eventually, perhaps there will be a $1-2K compressor that's really great, runs reliably for years, and puts out near breathing quality air, as more and more people get into PCPs. The AV 4500 is a two-stage Chinese compressor in a nice case with some level of support. I am saving for an Alkin and I feel I am in a slow race between saving and my next compressor failure.
That's all I got.