The TH-F6A will get SSB, but you trade in 6m tx for it. HF RX on HT's isn't really all its cracked up to be without a proper antenna. You could use one of those miracle whips or similar active antennas but they don't come cheap and really cut into the stealth/portability factor of an HT. It is useful if you are interested in any sideband on VHF or UHF, but again most SSB stuff on those frequencies generally goes hand in hand with a real antenna as weak signal and satellites require beams.
While most radios can be modified, not all have extended receive capabilities that extend into the lower VHF band where the base of some DT systems transmit. Also, while many now have dual VFO's, even fewer will let you RX and TX at the same time. Other things to consider is if the radio has the capability of scanning CTCSS or not, and how fast it can do it. Of course you could go and try every single one instead as there's not so many PL tones as there are DCS codes. The newer DT systems like those made by 3M run WFM up in the 900 MHz band. Many HT's can receive them okay, but very few transmit there, and ones that do WFM out of the box are probably nonexistant. 900MHz is not a very popular amateur band at all and there was hardly any off the shelf voice equipment for it ever made, and it was all narrow FM if it was voice at all. Commercial gear is probably modifiable to be used for DT systems as the public safety band is not too far off.