Ubuntu -> LMDE: migrate packages using `aptitude` alone?

[Tom Roche <Tom_Roche@pobox.com>]

summary: I'm preparing to migrate a laptop from Ubuntu Lucid to Linux
Mint Debian Edition 10 and want to have the same packages (c.p.) active
after the migration. I believe I know how to migrate the packages using
`dpkg` and `apt-get`, but would prefer to migrate the packages using
`aptitude` alone. Is this possible? Are there reasons not to do this?

details:

I've been running Ubuntu on a laptop mostly happily for some time, but
have wanted to get

* proprietary multimedia working "out of the box"
* "rolling releases" (aka, more updates without upgrades)

So when I heard about LMDE, I immediately tried it, and was pleased to
see that everything (that I checked, anyway) worked OOTB (i.e. when
booting the live DVD).

I'm now preparing to migrate Ubuntu -> LMDE. The box has separate
root and home partitions, so to CMA I first made

* images of both partitions (using clonezilla)
* backed up /home (with a script using partly `duplicity` and partly just `rsync`)

The final thing I believe I need to do (please suggest anything else I
should know) is to backup the list of currently-active (installed and
selected) packages so as to be able to restore them quickly and
completely in the new environment, so that I don't need to manually
install, e.g., chromium and emacs. Am I missing anything? If not:

>From other reading, one way to do this is

# in terminal in ubuntu
dpkg --get-selections > "${PACKAGE_FILE}"
# in terminal in LMDE
sudo dpkg --set-selections < "${PACKAGE_FILE}"
sudo apt-get dselect-upgrade
sudo aptitude update
sudo aptitude -s full-upgrade

Is that correct? If so:

I've been managing its packages exclusively with `aptitude` and would
prefer to continue doing so. I'd like to know,

1 Is there a way to do all of the above using only `aptitude`?

if not,

2 Is there a way to do all of the above using only `aptitude` and `dpkg`?
  I.e. is there an `aptitude` equivalent of `apt-get dselect-upgrade`?
  FWIW I don't see that argument in `info aptitude`.

alternatively,

3 Is there a reason to prefer the [`dpkg`, `apt-get`, `aptitude`]
  workflow above to a purely-`aptitude` workflow for this usecase?

If possible please reply to me as well as the list (I'm on the digest),
and TIA, Tom Roche <Tom_Roche@pobox.com>