These issues must be taken seriously by HTC/AT&T
I've read through this thread and have tried everything. Thanks all for the great feedback. Showing up this late on the thread has saved me a lot of time. Still, I don't think there will be a viable solution until HTC and/or Microsoft release appropriate patches to address these issues.
My main concern at this point is the WiFi reliability (or lack thereof). I own many smartphones, all of which work on my wireless N network. These include iOS, Android, and one other Windows Phone (the original Focus), so I'm feeling good about placing the blame on HTC. It's probably a driver issue. I'm speculating, of course, but given the fact that different combinations of antenna states (on/off) seem to impact the effectiveness of WiFi, it could be a driver for any of them or a combination of some. Long story short, I'm not holding my breath on a swift fix from HTC.
I'm also having the disappearing keyboard issue once in a while, but I can deal with that one, only because the WiFi issue hurts so much more. The 4G (HSPA+) is much slower than it should be for me. Until last Wednesday, I was using a Motorola Atrix 4G that was incredibly fast. I'm not thinking AT&T is throttling Titan phones, but rather there are some obvious antenna issues that need fixing and are probably impacting overall signal quality regardless of type (WiFi, 4G, etc.).
Just to add to the basket of data, my Titan does have a tethering plan associated with it which I have yet to utilize. I have only owned the phone since January 5th, and still my issues presented themselves right away. My WiFi setup consists of a Belkin Wireless N router using WPA2-Personal with AES for authentication.
UPDATE:
I've tested the WiFi on a handful of networks and now I feel like perhaps the metal enclosure is having an impact on the WiFi range. Turning antennas on and off just results in the same inconsistent results as leaving things alone (at least for me). When I'm close enough to my router, the Titan works beautifully. When I'm downstairs, my connection is unreliable. The Samsung Focus I have works no matter where I am, which has a thin plastic enclosure.
As for the HSPA+ slowness, it seems that my home signal isn't that great. It performed well outside of my house. I also ran a tethered speed test and was seeing speeds between 4-5 mbps down and 1.3 up. I good with that.
The disappearing keyboard has also surfaced, but it's really not that annoying (yet).
Last, the audio sounds terrible if I don't keep SRS enabled. This is the opposite of what I've read from other users.
Overall, I love the phone and don't see any problem worth returning it for at this point. Hopefully my assessments are good enough to hold true and not haunt me later.