I’d certainly not let the luggage options put you off buying the S-type Brompton as this is by far the nicest to ride of the Brompton models.
As the saying goes
"One man's meat
is another man's poison". As a slightly older man and one who has had back problems, I couldn't possibly cope with the low riding position of the S-Type bars. I guess the P Type cater for both perspectives. As for me I love riding my M3L with its sit up and beg position
I have the C bag and have read stuff about it not fitting on S Type models.
Regards
Jerry