[Nexus One General] flarbear:
Here is how I see it:

Pros of regular Apps2SD:

- Everything can move there

- Stays mounted even when you mount your phone on USB

- Everything moves to SD, data and .apk

Cons of regular Apps2SD:

- (Last I used it on my G1 with Cyanogenmod) Everything must move there (which means it isn't available when the card is out of the phone)

- Need to partition

- Requires root

- What about paid app security? Does rooted apps2sd open up the potential for pirating apps?

- Requires pre-allocating SD space for it (can partition tools resize it after the fact? It's still more of a hassle to have to choose partition size and then maintain them later.)

- Data for some apps that maintain privacy information is now easily accessible on the SD card of a stolen phone and no phone lock passcode can help there.

Pros of FroYo Apps2SD:

- Works on every phone with FroYo

- Some apps stay on the phone for when SD is not in the phone

- Encryption used to protect paid apps

- Does not require partitioning

- Data stays on a protected internal partition where they can lock it down if your phone is stolen and the theif doesn't know the passcode.

Cons of FroYo Apps2SD:

- Must wait for app to enable it

- SD Apps disappear when you USB mount the phone or remove the card

- Data doesn't move to SD card

Almost all of the FroYo-pros and regular-cons are not of much concern to the readers of this forum I imagine. We're all (most of us?) here able to root our phones and partition our SD cards easily enough and the security of paid apps is only really important to the app developers and the providers/Google that enable their commerce. So, this post isn't meant to suggest that these are pros and cons that matter to the audience here, but it does point out why Google didn't just implement the flavor of Apps2SD that you get with custom ROMs.

The one issue that I think still might concern us is the issue of data security for apps that store personal information. Were they all encrypting it even when the data was stored in internal flashROM?

Many (most?) end users would not be comfortable or know how to repartition their SD card. Even when some of the recovery ROMs make it easy to repartition, that process will intimidate the casual users and there is a non-zero chance they could still screw it up (turning off the phone while it is happening, etc). It's not the sort of feature one adds lightly to a consumer device. So, Google didn't want to require that step to enable Apps2SD, but it would be nice if they would utilize an extra partition if it was available (perhaps through Spare Parts or some other "expert options" app).

Also, Google really cares about protecting the copy security of paid apps so they didn't want a solution that simply moved the storage to a media that the user could easily extract and copy. Encryption solves this, though, and it would solve it whether they use the regular FAT partition or an ext3/4 partition.

Still, for the first release, probably 80% to 90% of customers will not benefit from anything more than what they've done, and those who might want more, are probably already aware of how to get it.

Personally I fall somewhere in between the 2 camps. I rooted my G1 and sort of enjoyed seeing what Cyanogen was going to come up for it next, but I got kind of tired of treating my phone as a hobby and so I haven't rooted my N1 and just want to deal with stock OS for a while. I might get more out of a custom ROM Apps2SD, but I will get enough out of FroYo's version that my space needs should be OK for a while (if more app developers start enabling it). I actually like the fact that I can keep some apps on the phone as I do occasionally remove the SD card from the phone - I did so more when I had the G1 and I could do so without removing the battery, but the design of the N1 doesn't make that as attractive. I mainly removed it to use a faster card reader when I wanted to do serious file migration like loading new media. Either way, I'm OK with (the description of) FroYo's version (which, admittedly, I haven't played with yet)...