We took two MSRs (one Whipserlite, one XGK) to Peru in 2012, both had been used. Taken the Whipserlite by air to the Dolomites a couple of times once eariler this year flying with Jet2.Same experience as JB, no problems. Ensured on the way out that the bottle and pump were empty and ventilated for several days before hand and tried to air for as long as possible before return journey too. Packed them in the hold baggage and had no problems.
As said above, you should be fine as long as it's clean, and there's no fuel in either the bottle or fuel line.Make sure you take a maintenance kit - I once had to help a customer fix theirs remotely down a sat phone line, when they were in the middle of the atlantic doing some solo rowing challenge. They didn't have a kit and the stove was their only way of rehydrating their food!If you run it mostly on unleaded petrol, it helps to buy some Coleman fuel or white gas every now and then, this helps clean out the fuel line a little which will clog up over time.
Where are you going? Coleman fuel costs fuck all across the pond.
Related, but what's the deal with sharp objects(knives) in hold baggage? It's obvs packed safely