Can I just check my understanding here, etched Tech as in one that has the old diamond shaped logo etched onto the top cap?
If so, quite a few models had an etched head. There's an aluminium etched top cap and I'm guessing (because of the plating reference) that you have the heavier steel cap, probably married to a brass ball end handle? These were also matched with aluminium base plates and handles so there are various combinations made between the 1940s and 1960s before they went all aluminium in the 70's... that coincided with a change of etched logo to a simplified name with no diamond.
Materials used affect weight and therefore the shave so any replacement just needs to be the same combination of materials and it should shave the same.
Either way, Techs are Techs pretty much, they were made in such huge numbers that none of them are really that rare, and you can buy two or three for the price of a replate. They're often on eBay at £10 a throw, less if you're not fussed about a case, or here of course, Mertwe often has a load in stock.
I've had about 8 or 9 now and they all shaved similar, except the all aluminium which were so mild it wasn't funny, so I'd say buy yourself one or two unless you're attached to that one for personal reasons.