I have in total undergone 6 transfers - 1 fresh and 5 frozen - and these are my results

1st Transfer - Fresh cycle 1 x day 3 embryo transferred - Chemical Pregnancy
2nd Transfer - FET 2 x day 3 embryo's transferred - BFN
3rd Transfer - FET 2 x day 3 embryo's transferred - Ectopic Pregnancy
4th Transfer - FET 2 x day 3 embryo's transferred - BFP resulting in DD now 13 months
5th Transfer - FET 2 x day 5 embryo's transferred - BFN
6th Transfer - FET 2 x day 3 embryo'd transferred - BFP expecting twins in May 2011

So in my case I have had better results with Day 3 embryo's rather than my day 5's (even though I've only had 1 transfer using day 5's). I still have 1 day 3 and 2 day 5's on ice (we got 10 day 3's and 5 day 5's to freeze after epu) and in my mind I don't think my day 5's are strong enough.

In my opinion if you transfer day 3's and they are meant to develop further I would rather have that happen where it is suppose to happen ie: in you to give them the best chance of success, but saying that plenty of people have better results with day 5's and take comfort in the knowledge that they have made it that far.

I know you will in the end choose the best option that you feel comfortable with or like in Ferrals case the decision can sometimes be made for you. Good luck and I hope you get that magical BFP very soon.