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For several years before I snagged the Tamiya kit (THANKS, Donny!) I already had the SMER, whose doggi-ness by no means presented any obstacle to building/correcting it - in fact, quite the contrary. However I did hold off putting in the required hours because I believed - as even the original eBay auction had stated, IIRC - that the SMER mold was significantly underscale. Reputedly an easter-european repop of an ancient (Heller?) mold - in something more like 1/50.
Well, ancient it obviously is, but - unless the Tamiya SwordFish is also undersized - the SMER is (at least) every bit of 1/48 scale, as proved by the following, direct side-by-side comparison:
The SMER parts are those molded in the lighter gray, shown in each case above the corresponding Tamiya parts. While the SHAPES of the SMER (fuselage and particularly the torpedo) parts may be less ACCURATE than in the Tamiya - assumed in all cases to be the more accurate and true to 1/48 scale - the former are certainly NOT smaller, but if anything in fact slightly larger! Likewise if, perhaps due some other innaccurate parts, the SMER model builds up with slightly undersized overall length and/or wingspan, this is merely a case for (relatively minor) accurization - not a basic incompatibility with 48-scale.
In my personal case, holding off building the SMER kit all this time has worked out well, in that I would have bashed it into Ark Royal's (wheeled) SwordFish which immobilized Bismarck - for which the Tamiya kit will now serve far (better and) easier. Meanwhile the SMER can be revert to its intended floatplane depiction - representing Warspite's historic first aircraft to sink a U-boat, in the Norway campaign.
In general, however, the moral to the above is clear: don't believe everything you hear on-line - presuming everyone with opinions must be the "experts" - until you can SEE it for yourself!