Memorex will only burn at 1x instead of 4x -r

My first spindle of memorex -r (25spindle) burnt no problem at 4x . I went out to futureshop and got another spindle of same and they burnt at only 1x(while searching forum found there is man.difference-ric and cmc) My question is ,is it o.k to use that media that is only burning at 1x , it does take longer but I can wait. My last backup i checked through and did not see any real problems in the movie just fast forwarding through it though.Or should I take it back as being wrong type and get money back as I took one back already and replaced it with another of same spindle. (which burns only at 1x)I do realize now I will have to watch out for what is out there. Thanks and still learning.