You may struggle to get a mid drive motor in your carbon frame, some carbon frames have beefed up bb so you may not have the clearance.
I have both the tongsheng 500w and bbs02b750w I'd choose the bbs02 over the tongseng any day, purely on build quality, operating noise and the colour display. I have the bbs02b fitted to a full sus giant yukon 2 and it will go up anything in fact I find it overkill at 750w but it is a lot of fun.
I use it for both offroading and my daily commute which is between 50 and 60 miles depending which site I'm working on. With a 48v 11.5ah from eclipse, I've managed 60 miles on one charge, when I forgot to take my charger with me doh, obviously i had to manage my power usage quite carefully.
With 44t chain ring I can easily get up to and just over 30mph, I now have a 36t lekkie bling ring on it which has reduced top speed but made the whole package easier to ride without power, if I fancy a bit of exercise.
I considered the bbshd long and hard but im glad i didnt spend the extra money now, its quite a chunk of extra weight to be carrying around with more power than you will ever need but if its pure fun factor then i can see the appeal but for me it's came down to pricing and the fact that psw power were shipping from an eu warehouse so no issues with vat/duty although I didn't have any issues with my tongsheng which came direct from China.
At the time the price was £320 with the 850c display and free delivery not sure what it is now, but bbshd is going to cost you roughly £530 from em3ev plus the danger of getting nailed for vat.
That is in no way a slight at em3ev they were so very helpful to me while I was researching my builds, they really seem like a top company, unlike a southern English firm that shall remain nameless, I tried to deal with and were anything but helpful, being told that someone your trying to spend a chunk of cash with "doesn't do phones" makes one wonder what the after sales is like and it would seem the chap in question can't even do emails either.
So my advice would be get a bbs02b you could get two bbs02 for the same price as one hd if you get slapped with vat, then you could convert both bikes or put a hub motor on the road bike.