My experience of Tech instruction was ******* awesome - probably one of the most rewarding courses I've taken, and not necessarily a 'now you must continue to tech' type deal - in fact, half the class just took the courses so they would feel more safe diving redundant on rec dives.
As a quick rundown, I took about a year of training that was 'Sidemount/Overhead Sidemount/Intro to Tech' basically taught as one course - We had a mixed team of sidemount and backmount divers (they did 'Doubles/overhead doubles/intro to tech'), and covered stage handling, deco procedures, blind navigation and emergencies, blind OOG situations, general problem solving and so on.
I expected, coming from rec diving, that there would be like... distinct parts of these courses, with a card at the end of each (i.e you do 6 dives and now you have a Sidemount card) but actually it all basically ran together, and for about a year, with maybe 25 class dives and 80 odd 'training' dives we just continued building skills more and more and more, and the 'problem solving' components got harder and harder - dive 1 of sidemount was like 'here is how you share air', whereas class dive 25 was more like 'ok you and your buddy are placed inside a sunken VW Golf and blindfolded. The instructor shuts off buddy's air, and now you have to figure out how to get out of the Golf, recover the stages left outside clipped to the line, follow the line back to the training platform while air sharing, then do 3 levels of simulated deco stops' 'oh and your stage regulator just broke as well'
If you'd told me that I was going to do the activities from dive 25 on day one, I would have just laughed. but a year later we just kinda shrugged and did it because we knew how to.
Obviously when I took Cave 1 straight after, a lot of the diving skills were already ingrained to the point where we were able to focus a lot more on just specific cave skills instead of basics, which is exactly WHY our instructor teaches intro to tech like that.
I would absolutely recommend taking such a course if you want a bit of a challenge, and to KNOW that you know how to solve problems underwater - as well as to get the most out of your sidemount rig...