I've not had lingual brackets, but have patients who do and there results are as good as with traditional brackets and they have the advantage of being the only invisable form of orthodontic treatment.
Speech is usually affected to some degree, but how much and for how long depends on the person. I have found (from talking to patients), that those who spoke the most, found their speech improved quickly. I'd definitely not recommend taking a week of work, as that's what people do when they're sick and getting braces is to improve your bite, not to fix being sick!
We have quite a few patients who wear ibraces on the top arch and ceramic on the lower arch. With most people, the lower arch is barely noticable and this is a good option as long as your bite is suitable for lower ceramic brackets.
If you're still uncertain of what to do ... please have more consults, until you find an orthodontist you feel confident with and can communicate easily with.