Another big Technosoft fan here.
My fave games are TF IV, TF V, TF AC, and of course Herzog Zwei. It was the first real-time strategy game, and one of the few of the genre I love to death.
I love the soundtracks of the ThunderForce games.
Also, I've played the original ThunderForce game (tape image) using an obscure DOS-based PC-88 emu that I've found on a TF fansite... basically, it's another take on the Bosconian top-down formula, but it's a hell of a lot more difficult. If you listen carefully enough, you will hear a couple of typical Technosoft f/x samples (shots, explosions, etc.) in it that they used in later games, even in TF V, just like Wolfteam did with some of their signature sound f/x.
Technosoft, like Wolfteam, always were micro computer/console-only developers, probably that's why their games never reached major parts of the general gaming public. Even during the 80s when the whole world was pumping tokens into arcade games, Technosoft stayed home system-exclusive, another reason why TF IV on Genny still is one of the best-looking horizontal shmups the console has to offer and pushes the machine to its limits - when other companies that only had some experience with various arcade boards finally started creating games for the promising home console market, Technosoft already had more than ten years of experience in squeezing the last bit of power out of heavily limited hardware.
That said, I also like TS's only arcade game ThunderForce AC, it's more or less a souped-up version of TF III, but I dig its gameplay and the artwork.
Too bad that they are no longer around... another creative team that I really miss.
TF V - Perfect System is one heavily underrated game, btw. About the differences between the SAT and PSX version, well, TF V is subtitled "perfect system" on PSX with a reason - it's an officially Technosoft-authorized final version of the game, and after playing both the SAT and PSX version a lot, I wholeheartedly agree.