I tested each polish over black (Wet n Wild Wild Shine Black Creme), green (Barry M Mint Green) and white (Beauty UK Frozen Kingdom) using the polkadot full nail image from my born pretty fauxnad plate M79 on white cardboard.
Apologies for poor light quality. I still need to figure out better camera settings for evening lighting.
312 - Gold - Gold backstage - transfered well, and stamped well over all colours
311 - Silver - Metallic Crystal - transfered well, but wasn't opaque enough
150 - Red - Red Tango - transfered well, stamped well over white and green, not quite opaque enough over black
322 - Dark Pink Creme- Vintage - transfered well, stamped well over white and green, not opaque enough over black
344 - Lilac Creme - Grape Fit - transfered well, stamped well over white and green, not quite opaque enough over black
326 - Coral Creme - Orange Crush* - transfered well, stamped well over white and green, not quite opaque enough over black
205 - Metaliic Lilac - Purple rain/Hip pop* - transfered well, stamped well over all colours
313 - Indigo - Fatal Plum/Blueberry - transfered well, stamped well over all colours (although black base is too dark)
060 - Turquoise - Hypnotic Turquoise - transfered well, stamped well over all colours
320 - Perwinkle blue - Blueberry/Popfiction* - transfered well, stamped well over all colours (although black base is too dark)
420 - Dark Grey - New Black - transfered well, stamped well over all colours (although black base is too dark)
251 - Bronze - Electric beige - transfered well, stamped well over all colours
In summary, the only polish out of the 12 I have that was not good for stamping was the silver, which was disappointing. I guess if you wanted a subtle look over a darker colour you could use this, but it wouldn't be suitable for an intricate design. Out of the rest, the gold, metallic lilac and bronze worked the best over all colours, although the bronze and gold are quite similar. The cremes weren't great over the black, but were still visible. I hope this has been helpful!
I also wanted to show you the "set-up" I use when stamping. After playing around a few times, this is what I find easiest, but I welcome any suggestions!
On the left I have a dish with a capful of polish remover, a cotton pad soaked in polish remover, a dry cotton pad and some cotton buds. If you set it out this way you don't have to touch any remover with your hands and potentially ruin your manicure. I use the wet cotton pad to wipe the stamper and scraper inbetween stamps (I just leave it on the plate and wipe the stamper/scraper against it to avoid picking it up), the dry one to wipe the stamper, scraper and plate with, and the remover and cotton buds to clean the image plate with, before wiping off any excess with the dry cotton pad. Then you can see an old gift card I use as my scraper. I find this easier than using the scraper you're meant to use as it's flexible, and it doesn't scratch the image plate. Then on the right hand side you can see my stamper, image plate, more cotton buds and a nail buffer. In desperation when I was starting out I stalked around youtube looking at konad tutorials and found this. I wasn't sure if it would work, and I didn't want to ruin my one and only stamper, but it did help. I just gently run the old, blunt shaping side of this buffer across the surface of the stamper every now and then (say, every 3 or 4 manicures) and it somehow helps it pick up the polish better.
Sorry this has turned into a bit of a long winded post, but I think I covered everything I wanted to! As I pick up more Miss Sporty polishes I'll test them out and add them to this post. Let me know if you give any a go and if they're worth having for stamping. For such a great price you can't go wrong, and they're all nice polishes anyway, so even though the silver didn't stamp well like I hoped I'm happy I have it!
I would like to thank The Manicured Monkey for helping me with suggestions for stampy polishes when I was about ready to give up. If you click the link you'll get a list of polishes she successfully uses for stamping. A lot of China Glaze and O.P.I there though, so if you don't have easy access to them give Miss Sporty a try! And if you have any suggestions/links for other good UK stamping polishes, I'd love it if you'd share them in the comments :)
If you've read this far, thanks! Hope I've been at least a little helpful :)
(I figured I should just say this products were all bought with my own money and I am not affiliated with Miss Sporty in any way, I'm just sharing my experiences in the hopes of helping someone out :) )