Now Gary...
Just as an example that it is not ALWAYS true, both the Miniarm T-72B front Glacis and the SP Designs T-72A/B glacis have been compared side-by-side (not by me, sorry, so no pics). The concensus, by a EXTREEMLY impartial judge, was that the SP Designs piece was ever-so-slightly better in detail and casting quality. While the Miniarm glacis does come with K-1/3 ERA, it is a difference of price of $50.00 to $5.00. Really.
But don't let that fool you into thinking that ALL similar conversions are the same. The Miniarm T-72 tracks run $40.00 and the SP Designs link-n-length runs either $7 or $8. But the Mimiarm tracks are superior. They are clickable indi-link tracks with better details and better casting. The extra $32 will get you a better product with less work to use on your model.
But I will let you know that I do not buy them as I just do not have $40 to drop on just tracks for something that 99.999% of the modellers looking at the built kit will not know the difference, even Soviet tank-o-philes. Once under a coat of paint and chalk/pigment, the difference just does not show as readily. Yea, I have already had this happen with some MT-LB tracks and people asking if they were Fruils...nope, just well cleaned up SP Designs tracks.
Now I am not trying to argue against Gary in this either...he is absolutely right. Miniarm makes GREAT conversions, the Lambourgini of our niche. But many of us can only afford Saturn's. Like SP Designs (or, shudder, AEF Designs) or Verlinden...etc. Neither set of companies should be punished for serving different niches of our hobby.
And it is not like SP Designs is making a intentionally inferior product, or using too many shortcuts, etc...I make sure that Sergej does not slip and if he ever should, I would stop selling kits for him.
But I think I know where some of the grief comes from too...those T-80 conversions. Sergej has put out a good conversion for a good price...but they are a BEAR to work with, and there are some current casting issues that are being worked out. Once they are solved, things will be better. This does not make the T-80 conversions unbuildable, but it does make them more work than a expensive but easy Miniarm conversion (when they get the T-80 sets out that is). And even they will be compromising as they are intending, so far s i know right now, to build their conversions on the Zvezda kits...which have problems that I am interested to see them solve without making a whole resin kit.
And finally, we in the US often loose sight of what the primary focus of the kits are for. SP Designs, for example, is for Eastern European consumption first, and Sergej does VERY well by them. So well that his shipments to me are getting more spread out as he is casting more and more for the EE market. And he has said to me often that the way the T-80 kits are set up is the way his PRIMARY customers want it. Really. I wanted him to cast the engine decks without the screens so they could be added in, for example. He said he has been told that doing that would DECREASE its appeal to his EE customers...so it does not happen. An example of this is kit 081 T-80 tracks. He has sold ~100 sets in the USA/UK. He has sold over 500 in EE. Guess who he listens to?
And so...
(And even I have a hard time remembering that SP Desings is not my own private casting house! I have great detail ideas that are not practical because of lack of salability. BUT I got him to make the T-72 Glacis conversion and the M107/M110 tracks, thank you very much!

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That is enough hot air from me for now...