I think the fare differential (especially taking into account the A/D class surcharge for an xONEx) will make it almost worthwhile to commence the RTW in AMM (if you don't want to bother with the logistics of KTM). It also has the added advantage of booking via AA thus avoiding fuel surcharges when compared to other airlines.

Assuming you are travelling on an Indian Passport, your biggest "hassle" is going to be obtaining the various Visa's required.

Here's a one ex-AMM itineraries to consider

AMM-LHR-SYD-NRT-DEL-HKG-BOM-HKG-JFK-LAX-DFW-ANC-DFW-LAX-LHR-MCT-AMM - 58703 BIS miles