Property taxes are definitely a concern when selling a home in Indianapolis. The assessments often do not make sense as stated by Tony.
When calculating any decrease in property value, based purely on taxes, you would have to narrow it down to individual neighborhoods. Or, at least, I would. There is really not a standard for Townships.
Since you specifically asked about Meridian-Kessler and/or Washington Township, I ran a few statistics for sales in Washington Township for 2004 and 2007.
In 2004, before the new assessment, the averages were:
2 bedroom, 2 bath with 1768 sq. ft.
Average sales price was $180,840
Average days on market were 65
For 2007, The averages were higher, though, not much.
2 bedroom, 2 bath, with 1728 sqaure ft.
Average sales price was $187,391
Average days on market were 82
As you can see, the averages indicate an increase and it is taking about 20 days longer to sell. These numbers will change as you narrow down to specific neighborhoods.
If you would information about specific neighborhoods, I'd be happy to research the data for you.