The way I've been playing it has been that the technology level is separate from any inherent quality, design, or material modifiers. Thus you could in theory have a +5 design bonus, a +5 material bonus, and still be an early tech design.
I am actually working on some ideas for working with obsolete tech in a game. Such as buying a ship that has early reactors, when the current technology is mature. Parts availability can be an issue for anything you can't fabricate yourself, maintenance requirements goes up, but the used price drops significantly (which can make it easier for a party to buy a vehicle). But then of course you need to know just how hard and expensive it is to replace said obsolete component after the players come into some money too.
Going the other direction is a problem too. The party finds some alien advanced tech and integrates it into their stuff, or get a hold of some prototype (which should probably have quality issues of its own). But maintaining and fixing it is a huge problem because the support information and infrastructure doesn't exist.
Note: I wouldn't use the Harp Normal, Improved, Master rules. I would use the improved quality and design rules from Harp SF instead.