I'd say you should try to recruit everyone.  Language is not a barrier because this is a global business with lots of language-related tools to help each and every one of us understand and succeed.  
To limit your recruitment to english speakers will harm the growth of your SFI business as can be seen on the table below.  Observe the biggest native speaking people in the world.  These are people that you will miss out on if you limit your recruit to English speakers only.
  
George H. J. Weber's report on the number of total speakers of the top languages
Language	Native speakers	Secondary speakers	Total
Chinese	1,100 million	15 million	(not a significant difference)
English	330 million	150 million	480 million
Spanish	300 million	15 million	315 million
Russian	155 million	125 million	280 million
French	80 million	190 million	270 million
Hindi/Urdu	250 million	 ?	 ?
Arabic	200 million	20 million	220 million
Brazilian Portuguese	160 million	30 million	190 million
Bengali	180 million	 ?	 ?
Japanese	110 million	10 million	120 million
Punjabi	90 million	 ?	 ?
German	100 million	10 million	110 million
Javanese	80 million	 ?	 ?
                                                    
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                        I'd say you should try to recruit everyone.  Language is not a barrier because this is a global business with lots of language-related tools to help each and every one of us understand and succeed.  
To limit your recruitment to english speakers will harm the growth of your SFI business as can be seen on the table below.  Observe the biggest native speaking people in the world.  These are people that you will miss out on if you limit your recruit to English speakers only.
 
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