I posted this on another forum but also wanted to post here in the hopes of maybe a difference audience as well.
I've never had the chance to use frozen before, always either live cover or fresh cooled in the past. Now, I must admit that I'm leaning very strongly towards using frozen because of the ease, it's there when my mare is ready, no worrying about MTW collections or Fedex plus it opens up more choice in stallions.
Drawbacks of course are making sure I pick a stallion who freezes well and usually no LFG.
I've done both. If you have frozen semen that is known to have good fertility (and by that I mean, the semen has resulted in many first try pregnancies, not just that the post thaw motility looks good) and you have a vet who is experienced using frozen, has a good track record with getting mares pregnant with it, is willing to ultrasound every 6 hours, even in the middle of the night and hopefully can do deep horn insemination, than I find that frozen works out to be more cost effective and convenient. No worries about shipments getting delayed. The price per dose is usually significantly cheaper than a fresh semen contract. Also, you can buy multiple doses at the same time and only pay for shipping once. The vet fees per cycle do tend to be more expensive due to the greater number of ultrasounds. However, if you are unsure if the fertility of the semen and you don't have a good vet, you may be throwing money down the drain. Fresh cooled is nice because it come with a LFG and your vet costs will likely be lower. However, keep in mind if your mare does not catch on the first try, you will need probably need to pay another collection fee and shipping for the second try. Depends where you are and the stallion is, but this may end up being several hundred dollars. In may end up even being more than a second dose of frozen would have cost you. I am in Canada and I bred to a stallion in Kentucky last year (dealt with all the CEM hassles, yikes!) I figured it out that it would have cost me an additional $800 if I needed a second shipment of semen, yikes! (collection fee, additional fee from the SO to take care of the CEM paperwork, shipping, customs broker, courier from airport to vet) Thankfully the mare caught on the first try. My policy now is that I only breed with frozen semen with a proven track record or fresh semen from Canadian stallions.