Thank you for your question.
Most of my uniform parts are modern reproductions. I go for higher end ones, mostly from Voin. A lot of their stuff can be made with period materials, and even their reproduction materials are very close, especially the cotton. Some other vendors excel at other items, such as ammo pouches and so on.
I choose reproduction uniform parts for a few reasons: Firstly, pretty much every item I could ever want is readily available. Some original items are quite rare. For example, an original ABTU canvas jacket. Secondly, they can be tailored and I don't have to spend a long time looking for originals in my size (which is a fairly common 50-4 for tunics, but still). Thirdly, they're guaranteed to be in mint condition because they're newly made. Thus, I won't have to worry about them falling apart at the seams like I might with originals. Leather items like belts and map cases are usually in poor condition. Fourthly, originals are almost always more expensive than reproduction items and that means I don't have to worry about ruining the reproductions as much as I would originals because they can be replaced for much cheaper and easier.
My chrome boots are original but postwar and look fine bar the soles. It's very hard to get original ones in wearable condition for a reasonable price, and totally faithful reproductions are too expensive to justify for me when I can get sufficiently accurate postwar ones for 25% of the price of reproductions. I have an original underwear set, too, which are super easy to find.
Where possible, I try to use original uniform details, such as buttons, cap badges, and so on. I won't wear original medals, badges, and awards, though. (Guards Badges would be exempted if I ever needed to wear one).
Spectacles have similar problems. I don't have original period ones because nobody will reglaze plastic originals due to the chance of breaking them, and they're usually fairly expensive depending on the style you want. I own period accurate modern-made ones (bar the anti-glare lenses which I intend to have replaced). I had reproduction dienst brille (see picture 3) but they were so uncomfortable that I had to replace them.
I don't own any weapons, but we have a group quartermaster who owns a number of original deactivated weapons. Two of them, a PPS-43 and DP machine gun, are postwar Polish, but are pretty much identical to wartime originals. They're substantially cheaper and easier to find than period examples with minimal visual downside in terms of accuracy. Reproductions of certain rare weapons would be fine, such a a Luger, AVS-36, and so on. A few replica grenades are used because of the expense and usual poor condition of deactivated originals. I'm personally not that interested in weapons. I'm a cultural historian and there's not a great deal to be said about weapons in this context.
I also have a pretty decent collection of original and reproduction small items such as stationery, mess kits, hygiene kits, rations, tobacco-related items, and so on. Reproduction items are chosen when originals are scarce / impossible to find (like hygiene kit covers or gas mask lens sweetheart photos) or when I need to actually use the items (like notepads). I try to stick with originals as much as possible. I also have replica CPSU ID and commander's ID. If I can replace the original items for cheap, then I'll use them. EG an original Pravda might eventually get worn out beyond use, but I can replace it easily. I'll post a picture of some of my collection. I also use some postwar items which aren't too obvious and fill a useful role in displays.
The reason I want an original watch is because I've not seen any really compelling reproductions, I try to go original where I think I should, and I can afford one.
The first picture is of me as a Mladshiy Politruk (ranked up to Politruk because I realised it was a rank for Komsomol members only). I have a very long post explaining this role on our facebook group:
https://www.facebook.com/101910404620934/posts/155434005935240/
The third picture is a Leytenant of the ABTU.
