Susan,

I think your word fits this best. Iffy.

You have several things to be concerned about here.
Customs in EWR - Hit or miss. Could be long lines, could be fast, but I'd allow at least 1 hour to collect bags and get through customs.

Traffic-You would be stepping out into NYC rush hour. EWR into the city would technically be against the major flow of traffic, but they reverse many lanes of the river crossings to handle the rush, so you will still get caught. Then you have to get out the other side to Queens.

Check in at LGA- again lines. Could be long check in or security lines.

If everything goes perfectly, you could have plenty of time, but if everything doesn't, you'd have no chance....

Also keep in mind that a Taxi or Car from EWR to LGA will cost you more than $100 each way. That's enough to really figure into the total ticket price.

There are several ways to get between the airports that have been written about here at length and people will probably add, but if you have luggage, a taxi really would be the only reasonable way, but I would really try to avoid this transfer. There's got to be a better way...

In fact, here's one-
For a price similar to the SAS flight, there are a couple of other options.

AA is selling a fare via ZRH to JFK, where you could get onto Jetblue to MCO

It's got a layover in ZRH, but total price is very close to the SAS with the EWR/LGA connection and your connection is spent sitting in one place instead of schlepping around NYC at rush hour.