IMHO; and in my own experience there are 3 things I always keep in mind regarding "cheap" residential systems (unlike big projects):
1. I buy myself the "cheap" system first and test the crap out of it internally before offering it to my customer. On the least I've familiarized myself with the software interface enough that even if the customer calls me on the phone while I'm driving out on the road I can at least "try" to direct him/her with whatever he/she is trying to do at that moment (most commonly how to extract videos and save it to a USB drive for the police, etc. or how to disable annoying video lost beeping alarms until my technician reaches on site to fix the cause of said video lost event). On the most, I can do a 2 hours post-installation training for the end user and his/her spouse/sons/daughters/grandma/grandpa on how to effectively use the system everyday and get the most advantage out of it.
If buying and testing first is not possible, then...
2. I give customers 2 or 3 price quotes at the same time always and let them choose themselves. If the customer is too indecisive and ask for my recommendation, I tell them to buy the most expensive they can afford (maybe they´ll choose the middle-priced one or maybe the highest priced, they decide, not me). If they still insist, I'll recommend the highest priced one: not necessarily the highest priced will last longer (fanless heat dissipation problems, electrical issues on the house/neighborhood, storage temperatures, dusty environment, etc. but those are another topic) but the customer will certainly get more features and sometimes more years of warranty with a higher price. All of this is because I've met many customers that have "unreasonable" expectations regarding cheap systems and some are experts blaming us later as "bad" professionals that recommended them "bad" systems, when in reality they didn't want to pay much in the first place, so I give them choices and let them choose.
3. If the customer buys herself their own system on Amazon, EBay, etc. and just pay me to install it, I'll do it but of course I won't warranty any of the hardware/software bought elsewhere. I just assume the customer did his homework and checked the online reviews before purchase and it is their sole responsibility to have decided on that system. Again, as a professional one has to be wise and intelligent enough when dealing with potentially "bad"/unethical/tricky and cheap customers while growing one's business and shielding it from unfair clients not willing to pay much for professional services/hard-earned years of experience...
All that said, I won't go with any particular technology (HD-TVI, HD-CVI, AHD, etc.) just because of it's market share but rather with the mobile apps that can give my customer the BEST user experience possible. If AHD has a nicer and easier to use app than HD-TVI, I'll recommend it because in the end I think the customer will judge strongly on the daily personal usage level and I have to say historically apps for standalone Linux-based cheap DVRs had been equally cheap and crappy to say the least ...