If you want an all band/multi-mode radio for portable operation, the 991a will likely work well for you. The compact form factor and the deep touch screen is not convenient for a daily use radio, where you might have desk space for a slightly larger radio with more user friendly and often used controls and ability to monitor multiple bands.
I owned the 991 model and while it had nice performance, it didn't fit my operating style. I didn't experience any hardware / software problems with the unit, but would have preferred the 991a upgraded live scope and waterfall.
The idea of a HF/VHF/UHF all in one transceiver appealed to me on paper, but not in day to day operation.The all/band mode function would seem to address desk space and be a Swiss Knife for portable operation, but was of limited use as only one band can be used at a time. I prefer to be monitoring VHF and UHF or the local repeater while working HF. An example of frustrating operation is that a simple switch between FM and SSB modes during the VHF contest required a mic level adjustment in touch screen menus without the benefit of instant switching between tracking saved settings.
The Wires-X operation is clumsy and not well set-up as is the FTM-400/300 or FT3DR radios. Not a daily use Wires-X or IMRS radio. That is a shame as the unit's cost basis should provide higher end digital functions. Not too useful for weak signal/satellite and more suited for regional simplex or repeater operation. I guarantee that you will overwrite more memory channels by accident than you will ever successfully save...
My biggest frustration was that the menus are stacked too deep and not organized in a logical flow. The combination of long or short presses is awkward and common settings are not located on the top level. For portable operation the power source voltage was very critical. If the supply voltage drops below 12.8Vdc, the SSB output would drop to 40 watts.
Nice to have all modes on 2m/70cm, but in hind sight, wasn't worth the sub par HF operational experience. For portable operation, I now run a 7300 for HF and just ordered a 9700 for VHF/UHF. If your primary interest is HF, my suggestion is to compare the 991a to a 7300. In my opinion, the 7300 offers significantly more and better features, a larger screen and better GUI. More 3rd party integration. For portable ops, no SSB output power drop until source is below 11.2Vdc. Then it is a 20-30w reduction until the battery drops below 10.2Vdc.
Doubt that you will see additional software function / features released for the 991a as the design is now 4+ years old and the competition is growing for SDR rigs. 991 software updates have primarily been fixes.
Hope this helps. I am not a fan boy of any brand, but know what works for my needs and preferences.
Yaesu 991 Portable
Icom 7300 RV Portable
Flex 6300 / SBE Expert 1.3 FA / PalStar HF-Auto
Flex 6400M During FD 2020