What is the benefit of autosomal and X STR tests?

Question

Family Tree DNA offers STR tests for yDNA, of course, but they also have STR tests for autosomal and xDNA.  I have some ideas on how this could be used but has anyone taken these tests?  Were they able to validate or invalidate a relationship?  

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Test Type	Marker	Price
Autosomal	CCR5	$39.00	Add
Autosomal	D9S919	$15.00	Add

 

Test Type	Marker	Price
X-STR	DXS10011	$10.00	Add
X-STR	DXS10066	$10.00	Add
X-STR	DXS10067	$10.00	Add
X-STR	DXS10068	$10.00	Add
X-STR	DXS10069	$10.00	Add
X-STR	DXS10074	$10.00	Add
X-STR	DXS10075	$10.00	Add
X-STR	DXS10077	$10.00	Add
X-STR	DXS10079	$10.00	Add
X-STR	DXS10131	$10.00	Add
X-STR	DXS10132	$10.00	Add
X-STR	DXS6807	$10.00	Add
X-STR	DXS7132	$10.00	Add
X-STR	DXS7423	$10.00	Add
X-STR	DXS8377	$10.00	Add
X-STR	DXS981	$10.00	Add
X-STR	HPRTB	$10.00	Add

Comments

Hadn't seen this before, thanks for pointing it out.  I look forward to hearing of anyone's use of this and what benefit they felt their received.

Answer 1

According to what I can read, mainly from ftDNA themselves:

1. CCR5 provided for novelty value only

2. D9S919  may assist in demonstrating Native American ancestry for 30% of cases.

3. the X-STR tests are also provided only for curiosity value and "not intended for genealogical studies". There have been scientific papers published with these paramerters and people might like to see how they fit in to the papers' conclusions.

If you and another person have matching segments of X based on SNP testing then I can't see how STR readings would offer anything extra. If the segments containing the STRs  don't match then I don't understand if it would offer anything of value.