I transitted at DEL in April without a VISA (which was permitted since I was ticketed for the first flight out to my ultimate destination -- Kathmandu), but it meant hanging out w/in DEL airport for about 9 hours. (Obviously your situation differs.)
I later regretted not getting a VISA because just one month later I returned to Delhi on vacation, this past weekend, and plan to return w/in the next year, at least to transit enroute again to Nepal, which I thoroughly enjoyed and can't wait to re-visit in order to do some serious trekking.
So for the 2nd trip (last week) I got a multiple entry Indian VISA.
Just my 2 cents worth.