Thanks Guys, I don't know what to say The decision to call items by there function is a poor choice if you ask me. Calling something an SD Mapper when MANY units can do SD Mapping is like asking for confusion. Similar confusion arose from other tech terms, You can see how i was confused. I also find this unit too expensive. I'm after the best bang for buck if i can find it. Initially its just a storage solution with Nextor but in time maybe id like to load ROMS from it. IDK. I don't want to buy something else in 6 months time etc. I don't have spare money to spend on MSX tech for the most part. FYI Ive secured a refund on the item i bought so there's that. Now i need to do some further research and educate my self on advances to MSX Hardware over past 40 years or so i guess. So right now I want a SD Card Storage Solution with Nextor DOS ? Additional functionality is welcomed but at this point i don't know what else is available or want. Ohh and can someone tell me what an SX-1 is ? As mentioned by Pentrou ?
Before figuring out best bang for your buck, figure out the list of best bang...
1 - GR8NET: does it still need a MSX? Has it all, Network, Mapper, Disk, Sound Interfaces... And Eugeny still works on it. There is nothing like that for MSX or any other retro-device that I am aware of.
2 - Carnivore: supports quite a lot sound extensions (except Msx Audio / OPL3 / OPL4), mapper, flash, disk, mapper... Also RSBC still supports it actively developing improvements
3 - Mega Flash ROM SCC+ 512KB: a quite good device, less sound devices supported than Carnivore
4 - (For me) a tie between SD MAPPER (1024 is better, 512KB is ok but you won't be able to use mega ram to map Konami mapper games seamlessly unless you have a separate sd card that boots DOS1) that has mapper and disk but no sound interfaces or flash/ Mega Flash ROM SCC+ (versions without mapper) doesn't have mapper but supports SCC and I think a second PSG (not sure) / Rookie Drive (just disk interface and nothing else, but Sourcer0r has done an amazing job implementing MSX USB support with it, but you would need a separate mapper to benefit from it): SD MAPPER allows Nextor, the others won't, but they have extra features (SCC for MFR and RD can do quite some stuff with USB devices, but without mapper you will be severely limited)
I've not mentioned other interfaces because those are not found to buy easily/normally, like Aquijacks...
Now, you need to figure out the BUCK part... For your region...
Thinking about the features you said you need, I would go with any option that has reasonable cost and allows you to use Nextor. If you think in the future you might want to do more than just programming and saving and reading files, oh well, my favorite cost benefit is Carnivore 2. If money is no issue, surely GR8NET is the best expansion made for any retro device, EVER... Can't tell how much amazed I'm with the work from Eugeny, constant work, always expanding and creating support for new devices like the recent MIDI and OPL4 support.
And about SD MAPPER and Carnivore 2, those are open hardware and as such you can find different suppliers with different quality... Try to get one from a reputable manufacturer if any of those are your choice.
Good luck finding the device you want, and, if you are too confused, just use an old mobile phone or digital sound recorder and save/write to tape, simple and effective, just make tests and adjustments before using it to save real work, as different devices will require different settings to work best. 
