True.. it was not a general statement across all brands. But when you compare direct-lit vs edge-lit on a specific brand, particularly in the entry level or mid-range bracket, uniformity is generally better on direct-lit. Every direct-lit Samsung I've seen has had almost perfect uniformity, and every review I've read of their direct-lit LCDs have said the same thing.
I've been a frequent poster at AVSForum for over 7 years with over 3500 posts, plus I have experience with dozens of displays because I upgrade almost every 2 years. Burn in or image retention varies from panel to panel, but it is more likely to happen on a plasma compared to a CRT in my experience. It is still rare, especially if you vary your viewing content a bit. Again, I just advise people not to go plasma if you're the type who plays hours and hours a day without viewing anything else. Considering AzBat got burn in on an LCD, I just can't recommend plasma.
True, LG direct-lits do have better uniformity than edge-lits, ditto for Samsung. It's when people mix brands and panel type and equate both that brings confusion. Take LG full local dimming LCDs for example, depending on how many dimming zones each uses (from 24 to 480 in LG's case) the perceived contrast differs tremendously. For example, last year's LG LM9600 used 24, but it stood no chance against even a Samsung CCFL because 24 dimming zones will not diminish LG's weak contrast ratio (900:1 to 1100:1) against Samsung. (4000:1 to 5000:1)
It was not my intention to imply plasmas are as burn-in resistant as CRTs. But, one sample, especially from a distant past, does not paint entire display type. It was incredibly rare, but a few old LCDs did suffer from burn in (I've seen a few, but they were all really old), but that's no longer the case. I was so used to seeing burn-ins from old Sega Model3 arcade games that used rear projection CRTs. The last CRT RPTVs from the 2000s never suffered from burn-ins either. (Convergence problems were more common) Plasmas were famous for having burn-ins during early 2000s, but also no longer a case. CNET tried to duplicate it but they failed. There are still IRs here and there, but they are temporary and the majority plasmas can be enjoyed with absolutely no IR, I know I was one. (and LG plasmas were notoriously known for having the worst IR) OLEDs will soon improve and reach where plasmas lie today. It's as silly as avoiding flat panels altogether and sticking with CRTs just because some has dead pixels.