Actually, at a local shop I would have the possibility to choose among some IDE/ATA slim writers (for laptops).
I already tried an LG GSA-T20N but despite the CD overburning support, it doesn't overburn DVD.
So, second choice was a PIONEER DVR-K17A (still in my laptop at this moment) but the same story.
The owner of this shop (mainly aimed at repairing activities more than selling) is very understanding and doesn't care if I test and bring back the writers. They all are about 10 years, kept in a small box and collected from old laptops probably dismissed. No one is going to ask any of them (except me). The first time he selected 3 writers with cover bezels identical to the original one (an old Sony).
After the PIONEER I could get a PANASONIC (UJ-841), but I've heard that Panasonic writers are not so good, at least not as the others. But I remember that there were other writers over than the 3 selected. They just didn't have the same dimensions of bezel (perhaps even a slightly different shape). Who knows... one of them could be the "soulmate"! Next time I'll make a note of those writers models: perhaps it's worth trying them, although I still have no evidence of DVD overburning support by the slim writers. But supposing that I upload a list of those writers everywhere on the internet, it's very difficult (if not impossible) to find someone who is able (or willing) to say whether and which support DVD overburning. Result: I should try them one by one (obviously, asking before this time-consuming activity is convenient and necessary).
Anyway, with the writers of this shop I could test any firmware modification, since the owner will hardly sell any of them (actually, he's really not interested in old writers that nobody still needs). So, no problem if I mess any writer: I could get another one for free. But I'm not intentioned to waste writers. As you rightly said, I need to know some specific information about firmwares in order to modify them where necessary. People with experience in firmware modding can firstly say whether the DVD overburning feature entirely depends on firmware settings or even (or only?) on building specifications.
If someone tells me that modifying the firmware is enough to enable DVD overburning and that I should change just a few istructions in the firmware file (I should be told which ones, since I'm not an expert in burner's firmware), then I'll do it. To give you an example, if firmware modding for my purpose is as easy as described in this article (http://mingersoft.com/blog/2012/05/hack ... ment-49671
) for letting a burner recognize a specific brand of discs, why couldn't I try? If successful, I would save time and I would be glad to have learnt something new about firmwares.
If there is a model from your manufacturer that has overburning, that would be your best bet but I still would not try it as it will probably brick your writer and then you have to buy another one.
Here I think you were referring to another possibility, less difficult than getting into the firmware file to modify it. You were talking about the so-called "cross-flashing". But again, it's very difficult (I'd say impossible) to get such information. It's easy to know that all (or almost all) the writers (at least the last IDE/ATA manufactured about 10 years ago before the introduction of the SATA's ones) support overburning. But manufacturers don't tell you if it's just CD overburning or even DVD overburning. So you'll never know if you can safely cross-flash between 2 different models, since basically you don't know whether there is or not DVD overburning feature (I'd add, most often there isn't, as far as it's been reported in the past), unless there is someone (in a whatever internet forum, for example) who can provide this precious information. But trust me, these fully informed people used to hang around forums many years ago. Now there is no interest at all in such issues.
I never had a Plextor or BenQ writer but I did some overburning with NEC, LG, Samsung writers on both CDs and DVDs with Nero.
Good to know! Do you even remember the specific models or just if they were external (so not for laptops)?