I am using Lightroom foto all my prints foto my customers. I have tested Mirage 2,3, andere 4, but in sheer printquality Lightroom is visibly better.
Aside from the printquality, the concept of print templates makes Printing with LR a breeze.
Zo if you already have Lightroom i see no reason to buy Mirage.
I see no reason why there would be any difference. They use the same driver. Sounds like the custom settings were not correct.
My prints are excellent and guys like Les Walkling (who is a print and colour management consultant to Epson) use Mirage.
As for Presets, that is really a strength of Mirage as you don't really need them. You can make droplets if you repeatedly make the same print.
Note Mirage deal only covers P800 and 5000.
At the end of the day you can download a copy of Mirage and try it free for 14 days.
I don't what countries the deal is currently in, but in Australia we pay a lot more than $845US for a P800.