what you need to weigh up is the difference between those HEN (homebrew enabler) and full CFW - and the implications of the TA-088v3 m/b of PSP Slim and the PSP Brite over all other models. i reckon that is the major consideration over all other differences in features between PSP models.
i have both phat and slim - no desire to get the Brite or Go!. I would avoid those two models i mentioned above, because i would want to run full cfw, instead of those HEN.
Sometimes I prefer the phat over the slim - i find the extra bulk and weight of the phat quite comfortable and real solid. i do notice when i switch betw models, the phat has different feel on the buttons (not because they are more worn out than the others). the slim display is better than the phat - so I imagine the Brite would be a slight improvement in graphic display than the slim.
one thing - isn't the Brite because of its brighter screen (and maybe other features) drain its battery faster than a Slim?
i didn't realise that there is a difference in the video output between the phat & slim but there you go. If you use this feature, video out, then i guess you would prefer the slim over the phat. you intend to play games on the bigger screen or playback some video files stored on the memstick in the psp to the larger screen?
you can tell whether a Slim has a TA-088v3 model by various means - though those limited edition bundles may or may not have these identifiers on its retail packaging. May have to look at the product itself - particularly in the battery compartment to figure out whether its that dreaded m/b model or not...
scondly, you don't need a pandora battery now to perform updates/downgrades cfw on the psp. still, pandora battery and mms is handy to recover a brick. check out Hellcat's Recovery Flasher - and its objective/aim of updating/downgrading/fixing cfw without using pb. you can make the pb using this Hellcat s/w.
finally, i have assumed from your post, you don't have cfw on your psp phat. if not, why not give cfw a go on that phat?