Your comments, unfortunately, are somewhat misleading. The Pro-668, along with other GRE design scanners, whether manufactured, originally, by GRE, or (as is the case for your 668, manufactured by Whistler, using the GRE designs), does not handle simulcast well. The GRE version of that scanner was the Pro-18, and the GRE labeled PSR-800, were able to get the
upgrade from Whistler that added P25 Phase II capability, as well as DMR. The Pro-668 had Phase II capability, but the upgrade, in effect, made it into a WS-1080, and added DMR reception capability. The Whistler branded models, WS-1080 & WS1088, had Phase II & DMR without an extra paid upgrade. Per your comments, you did have the upgrade done, but that does not change whether or not the unit can deal with simulcast.
This is
not to imply that your statement that the 668 works for you is incorrect. If the site in TxWARN, that you monitor in the Houston metro area, is
not simulcast, then the 668 would work. However,
Simulcast distortion issues are extremely location specific. If you are located very close (say a quarter mile or so) from a specific sub site (transmit tower) of a simulcast site, that strong signal may well override the out of sync signal from towers that are farther away. Or, something such as hills, or clusters or tall buildings, could possibly block the conflicting signals from multiple sub sites, leaving the scanner only able to receive a single site. In that case, the 668 or similar models can work. At other times, something in your house, such as foil backed insulation in the walls, or something metallic next to your scanner, or on the other side of a wall, might also limit reception to a single tower, allowing the scanner to work. In some cases, you can move the scanner around in your residence, and may find a sweet spot where the scanner will work. Sometimes, that can be a move of only a foot or so makes the difference between clear reception from a simulcast site, or no reception at all (or garbled reception). On the Simulcast Wiki
page are several different methods you can try to overcome simulcast problems. Sometimes, one of these suggestions works, at other times, none do.
HB-Texas, as already noted
above, most of your area's agencies use TxWARN. Depending on your location, relative to a specific transmit site, one of the suggestions might work, or maybe not. As already noted, the Tyler site is simulcast, though there are several sites in Smith County that are not. However, one of those might not carry all that you want to hear, especially if Tyler is one of your interests. Your best choice, if simulcast becomes a factor, is one of Uniden's SDS series scanners. Those are made to deal with simulcast. the next model "under" those, the x36HP series scanners (436HP & 536HP), are less effective on simulcast, but it can work in some cases. Besides my SDS100 & SDS200 scanners, I also monitor NTIRN, a regional system here in the DFW area, which has simulcast sites. I am able to receive the system reasonably well by using a specific antenna, and laying the scanner flat on my desktop. That helps reduce the distortion & allows the scanner to monitor the sites I'm interested in. While it is not 100% effective (the SDS scanners are), it does well enough to be useful. The P2 scanners (325P2 & 996P2) are less effective on simulcast than the x36HP units. The Whistler/GRE scanners are less effective, in my area, than any of the Uniden scanners mentioned above. That applies to the newest Whistler models. I have the TRX-1, handheld; the desktop/mobile version is the TRX-2.
Should you decide to try a model other than Uniden's SDS100 or SDS200, be sure to order from a dealer that does not hit you with a large re-stock fee should you wish to return a scanner that cannot handle simulcast problems. Another option, which would be the lowest cost, would be to use one of the SDR dongles & downloaded software (some versions are free), and use your PC or laptop to monitor the system. These handle simulcast problems, but obviously are not a portable solution. Your listening is dependent on having a PC (or laptop) available for use.