[bbDev] Tweaking template-functions.php and upgrading?

[Jaime Gómez Obregón]

Hello,

I'm working on a bbPress theme for my site, which I'd like to release
later. I want it to be XHTML 1.1 (no trouble with this) as well as
WCAG/WAI AAA compliant [1].

bbPress' easy templating and theming system is great for me, BUT I'm
finding some XHTML markup inside /bb-includes/template-functions.php
that I MUST change in order to fully achieve the W3C's accessibiliy
guidelines.

I'm afraid I did already find the same problem on Wordpress, when I had
to tweak a file outside the template directory in order to tweak some
markup for my needs...

So the question are,
a) Can I customize /bb-includes/template-functions.php without causing
no problem on the next upgrade? (I think no)
b) Can the XHTML markup in this file be changed by means of a plugin?
Should I write a plugin instead? 
c) Shouldn't be better to move this file (or a part of)
into /bb-templates/ on the next release, so template designers will have
all the power and control over all the generated markup, without causing
problems on upgrade ?

References:
[1] http://www.w3.org/WAI/WCAG1AAA-Conformance

-- 
Jaime GÓMEZ OBREGÓN
Director Comercial (jaime at iteisa.com)
ITEISA - www.iteisa.com
942 544 036 - 662 256 006