I have never used those, but I do have some Nextels that use SIM cards that are no longer subscribed. Off-network Direct Talk works find for my needs. If you snoop around a little bit you can find even more information, but the link below is for some previous posts. I think the best quality for legal, license free digital radios is the Motorola DTR410/550/650, but they are expensive. The used Nextels won't have as much range, but they are a little bit more affordable. The Triquares can be found pretty cheap some places, in fact I think Best Buy was closing out that or a different Tr0Square model. It just sort of depends how much you want to spend and what features are most important to you. If I were looking for legal, license free radio to use when I am ATVing in Nemadji State Forest, I would get some used Motorola HT1000/MT1000/JT1000 or something similar and program them for the MURS frequencies and set the power level accordingly. If I just want something to keep in touch with family members while shopping at the Miller Hill Mall, I would go with used Nextels on Direct Talk.
Edit: I looked a little bit further and found that the TriSquares are not digital, but that may not matter to you. Also, the Nextel can be used in Direct Talk even without an old SIM card. Look at the post from February 2010 on how to configure that. Oh, and the greatest range of an Nextels on Direct Talk might be the i325s. They have (had) a fixed antenna!