I'd recommend finishing your remaining supply of 16x discs and then switching to 8x. The 16x doesn't harm the burner but its more difficult for aging recorders to control their spin securely. Unfortunately Pioneers operate more akin to the Panasonic EZ series than the ES when it comes to rejecting 16x media they can't manage: a Pioneer will tediously insist on making four to six attempts to initialize the disc before it gives up and allows you to eject it. This can take up to five or six minutes, and listening to the machine grind away in vain causes much anxiety when you can do nothing to stop it. When the Pio finally does let you eject the failed 16x disc, its usually been rendered unusable. That alone is reason enough to go with the 100% reliable 8x media alternatives.
Pioneer did not go bankrupt because of its DVD/HDD recorders: they were and are very popular and good sellers around the world. What killed Pioneer was the one-two punch of the world economy tanking at about the same time women gained the upper hand in shopping for the familys large-screen televisions. Women have single-handedly destroyed the plasma TV market, because God forbid they should have a "horrible six inch thick display stuck on the wall". Once three inch thick LCD panels came down in price, plasmas became forbidden in all households. Before I'm accused of being sexist, this is the literal truth of consumer purchase patterns as studied by retailers like Best Buy and Circuit City, as well as mfrs themselves. Without volume sales of lower-end plasma displays to subsidize parts costs, production of Pioneers once-profitable Kuro displays went heavily into the red, then sales dropped to zero when the economy went south. Not being as diversified as Panasonic, Sony or Sharp, Pioneer could not save itself so it died.
All DVD/HDD recorders are complex beasts and the most technically-advanced pieces of A/V gear ever offered to consumers. As such, each mfr has had a lemon or two, or has an inherent flaw, and several gave up altogether in favor of hiring sub-contractors to OEM their current machines. In the brief history of these recorders, only two brands have managed to avoid major engineering problems or faults most of the time: Pioneer and Panasonic.
Pioneers expertise in optical disc machinery dates back to the laserdisc days, and they were among the first to market with DVD-R burners and media: so Pioneer was hardly a fly-by-night recorder source. The only bad machines released by Pioneer were the truly awful 2005 USA models 531-533-633, with their hopelessly dysfunctional and unrepairable TVGOS/HDD "synergy". Even these models are still in use by many AVS members: as long as they remain operational, they're good recorders, the problem was their hare-brained implementation of an immature TVGOS timer feature.
Panasonics have been equally solid and reliable, and wisely avoided the TVGOS trap Pioneer fell into (the Pannies used a completely separate electronic subsystem for the TVGOS which is not dependent on or damaging to the HDD). Good as they are, though, Panasonics have an extremely irritating tendency toward gumming up the disc clamps in their burners: they are excessively sensitive to finger oils and dust being transferred from the DVD surface onto the burner mechanism. This necessitates regular disassembly & cleaning, which your average consumer has no idea about unless they stumble upon DigaDos excellent tutorials here on AVS. So depending on your point of view, Panasonics could be perceived as "terrible" because their burners can break down in as little as six months. If you are aware of the dirt issue and are willing to perform maintenance, that perception changes and Panasonics become an excellent long-term recorder choice.
Its purely an accident, however, that the Panasonic dust-sensitivity problem can be converted into an advantage by someone who knows how to disassemble/maintain their units. Since they became mainstream in 2003, ALL brands of DVD recorder have had a finite and relatively brief usable lifespan in their burners, with most averaging 30 months before serious wear becomes obvious. In Pioneers case, and that of every other brand except Panasonic, the burners are not easily serviced by the user (if service is possible at all). When the burner goes, you're faced with a repair cost equal to purchasing an entire new recorder. DVD recorders are therefore disposable- period. They will not last your entire adult lifetime, the way carefully-used VCRs once did.
This applies even more to the vintage Toshiba, JVC and Sony DVD recorders which have more grief-stricken owners crying in the wilderness than Pioneer and Panasonic combined. There is no "perfect DVD recorder": every last one will bite a chunk out of your ass when you least expect it. Anyone who refutes this has been extremely, extraordinarily lucky with their recorder experience. A "brand X" recorder that runs five years without a hiccup is about as common as someone buying a new Pioneer thats defective out of the box: neither experience is typical.