[Transformer TF300T General] hgoldner:
There is a little lack of clarity which should be in the OP.

1. If a wipe is required (other than cache/dalvik), folks should know PRECISELY when to do that wipe. If NO wipe is required. it the OP should say so. I see a few posters in the thread who indicated that they did do a wipe, others who didn't mention it. A badly timed wipe can brick a unit; an undone wipe that is required can send one into a bootloop. It's an important detail --- and, for that matter, if the install script automatically wipes, then that should be stated.

2. It seems there is a difference of opinion as to the precise sequence of which flashes first TWRP 2.4.4.0 or 4.2.1 ROM (and it also appears it may not matter which goes first; (2) I saw one poster who made a big fuss about flashing the ROM via fastboot, but "flash system" will only flash the system partition, and the ROM obviously also includes a bootloader and boot partition.

3. Nobody has stated what I expect is the obvious (and there are any number of noobs running around and bricking their TF300's because they're not reading everything in the forums), but I expect this process WIPES the data partition, and therefore, all apps need to be reinstalled. I think I've seen only one poster who confirmed that he restored his backups, but he didn't state whether that was from Asus' backup software, Titanium, or some other method. Frankly, I like Apps2zip, but that's me.

Once I have some time, I intend to complete the process and then probably rewrite the entire standard operating procedure more clearly, but that isn't happening today --- and I'm still a little concerned about some bugs reported in 4.2.1 (including one involving hdmi out, and I must have working hdmi for work), so I'm not anxious to jump in whether others have clearly had issues.

Finally, I would encourage anyone already rooted and running Titanium to create a flashable zip of Titanium (it's in the menu options) and flash that after first booting the rooted ROM and preliminarily setting it up. Then return to recovery and flash the update which will install Titanium. Load Titanium, make sure it gets root, then point it to its former directory so it can restore the prior tablet device id (which will require another reboot). That way you won't use up authorizations on those apps that require device authorizations (e.g. Google Music, limited to 10, which is an issue for us flashaholics, or Amazon Market).

Ultimately, I believe the optimal updating method should be (note, I didn't say IS, because I haven't done this yet):

1. Make sure you have working fastboot on connect to PC; make sure you've backed up all your apps and data, make sure you've got the SupersSU flashable file and Titanium flashable file on the root of your internal memory (some are having issues with recovery reading removable cards). If you don't have the drivesr loaded, this isn't the thread for you, look elsewhere ("search" is your friend on xda) for how to load drivers, etc. By the way, the standard way to check if fastboot works "fastboot devices" does NOT work on the TF300T. Try to reboot the device within fastboot and if that works, you've got fastboot working.

2. Put updated ROM (4.2.1) on root of internal memory (apparently it works better if you actually extract the zip inside the zip downloaded from Asus, but that's not entirely clear either); let the system see the update from within the ROM and flash. That will probably factory restore your system (and delete all your apps and settings). Reboot to bootloader, connect to PC. Note that the new bootloader does not have the USB sign, the bootloader "defaults" to fastboot if connected to PC (this is actually more typically behavior for bootloaders than we had previously on the unit).

3. Flash updated TWRP in fastboot. Reboot to ROM. Disconnect from PC.

4. When ROM loads, do preliminary system setup. Reboot to recovery. (Some suggest that you can just flash SuperSU and Titanium, but I prefer doing things incrementally because if they break, you can go backwards to troubleshoot).

5. In recovery, flash SuperSU; flash Titanium. Reboot to ROM.

6. When ROM loads, set up SuperSU, make sure you have root; setup Titanium, restore prior device ID, reboot ROM.

At that point you should have 4.2.1, rooted, a working recovery, and be able to restore all applications in Titanium or howsoever else you like. If you're using App2Zip, this is when you'd reboot to recovery and restore the apps via zip.

That's theory. Will see whether that works in reality. Anyone who can point out a specific mistake, let me know and I'll edit.

One other thing. If you're not unlocked, DON'T DO THIS. If you don't want root access and a custom recovery, DON'T DO THIS. If you aren't willing to TAKE YOUR TIME, read ALL the relevant threads in this and other TF300T forums (the FAQ's are a good start, and there's a good itemized list of ROMs, kernels, firmware versions, too), then please don't just willy nilly flash things on your several hundred dollar tablet and then start yet another "I bricked my tab" thread. This is not for sissies. The Transformer is a finicky tablet. XDA is a "developer's-based" forum. You're supposed to SEARCH and do your homework --- otherwise, go to Android Forums or any of the other n00bfriendly sites and whine.

If you don't understand the language (this is a very international forum), find someone who does. Make sure you KNOW what you're doing. Like I said, I've flashed dozens of ROMs, recoveries, bootloaders, radios on many devices. I don't wade into this stuff. I don't do it when I'm multitasking, sitting in a class (I'm many years out of school), sitting in a courtroom (oh, well, all right, I did do a nandroid once in in court), talking with a client, sitting on the john. Clear the desk, clear the decks, focus. Or just leave it alone.