Sending through DHL should not be a problem.A friend did in June 2015 and got it back.The risk is the pickup email mostly enters spam box.So please be on the look out for it.I also sent mine from NAHCO DHL Office on 10th Feb and will be on the look out.Find below email He sent and response he got when he didn't get pick up email
9166xxxx
APPLICATION ID: E00017xxxxxx
I received a request from your embassy to send my international passport including that of my dependant's passports by either prepaid DHL or VFS on the 19th of June, 2015 , The passports were sent to your embassy using DHL on the 25th of June and it was received in your embassy on the 29th of June, 2015 and signed for by ERIN BROUSE, which made it a month and two days since I sent the passports I was told by DHL Nigeria today that I need a letter from your embassy before they can do pick up on my behalf, Also, I checked the online status of my application it has changed to DECISION MADE. Could you please update me if my passports are ready for pick up...
RESPONSE:
Dear Sir/ Madam,
Please note that your document is ready for pick-up. Kindly make an arrangement with a courier service to pick up your package.
A notice was sent to you on the 17th of July, 2015.
Best regards,
Wish every member still awaiting PPR Godspeed.