I've used the Sonic Thermal printables before and there are a couple different kinds.
I do not like Shop4tech's rating system, they only post good comments, but other than that I haven't had issue with them.
This media, depending on the media code you get is either crap or great. I personally recommend if you order them to request Media Code MUST001. The old discs were Longten001 which suck. Most people tried those a long time ago and cry about this media sucking...Sonic is just a name they use, the media code means more than the name. People need to learn about media before they bash a name or they end up sounding dumb most of the time.
As for these discs, if you get the MUST001's I can attest that they will burn great on NEC2500a and 3500 drives. I haven't used them on other drives. cdfreaks and forums.rpc1.org will have more info. You can also get hacked firmware from Herrie or a couple others to burn these at 8x on the 2500a, not sure about other drives. As for the actual disc, they are thermal printable with a clear stacking ring, and they actually have 4x printed on the stacking ring. Yes, they are sold as 1x-2x media but they have 4x printed on them and dvd-info pro lists the media write descriptor as 2x and 4x.
So it all depends on your drive. I have burnt well over a thousand of these to the edge while doing video editing. They work great as long as the media code is MUST001. For $0.15 a disc or so in bulk, these are my favorite discs. I've used RitekG04 and G05, they used to be good, but again depending on the plant they come from now, they are 50/50 at best...but they are an example of what a name will do for you used to be good, now just alright but still overpriced.
For the price, try a few and if your burner doesn't like them you've lost a couple bucks. But if they work like they do for me and a lot of other people then you'll have a new favorite media that is dirt cheap. Oh, and for everyone asking how long they will last...they are $0.15 a piece, get over it and burn another one in a couple years. For backups...if you are really backing up from data that is years old then you have issues.
That's all, and time to order more blanks. Anyone have a coupon for this month? They always have %10 off coupons every month.