What's best way to use Debian w/o my laptop? Flash + union?

[unforgettableid <unforgettableid@gmail.com>]

Hi all,

I usually get around my city of Toronto, Canada by bicycle.  I fall off my bike
once a year or so.  Therefore I don't carry breakable electronics like my
laptop unless I know I will need them.  But I sometimes need to use my Debian
OS, my files, and some shell scripts I've written when I'm away from home.  So
I invested Cdn$100 in a 16GB SDHC card to carry in my pocket every day and boot
Debian Linux from.  I used it for a year, but the card's write speed is quite
slow, so I've stopped using it.  I now have four options, and wonder which is
best.

1.  Use my laptop's internal hard drive to boot Debian from, and leave my
laptop running at home every day.  But this costs the environment, and the
electricity costs add up over time too.

2.  Buy a faster flash card.  If you do a Google search for [ cf iometer
benchmarks ] you can find some.  But this option might cost me Cdn$200 or more;
option 4 seems like it'll be cheaper and almost as convenient.

3.  Buy a 2.5" external HDD.  But I'm told that when these fall, they're much
more likely to break than flash.

4.  At http://rtr.ca/run_from_ram/ there's a tool that easily lets you use some
union filesystem on top of flash storage to speed things up.  I can set it up
to union my laptop's internal HDD on top, when it's available.

5.  I'm sure there are other options which I haven't thought of.  Feel free to
suggest more options.

Which option do you think is best?

Thanks in advance,
--unforgettableid