I too have been curious as to whether or not the EFI engines (single and twin) in the new XT Enduro Series will last as long as their carbureted counterparts. The problem may not be the OEM branded engine, but it's hard to ignore that companies like Kohler and Kawasaki who also offer EFI engines have DECADES of experience in engineering and building engines and are just better equipped to manufacture a robust, reliable engine. As for your original question regarding the K46, it is certainly not the cheapest, weakest transaxle offered in a riding mower, but it is not rated for any ground engaging equipment and will likely fail before any engine if you are going to ask it to do too much. Cub Cadet will sell a blade to anyone wanting to put it on their mower, but with limited torque from the K46 you will find that you will not be able to plow anything deeper than 6-8". I don't know what kind of snow you get, but we just had an 11" snowfall here is SE Michigan 3 weeks ago. Also, the transaxle is non-serviceable, like most of those found in sub $4,000 riders so any damage or potential damage done cannot be prevented/minimized with maintenance on the axle (albeit, some still service the K46 if they are daring). Its not to say that the mowers you are looking at are bad, but within a budget, you have the XT1/XT2 as well as all other made by MTD, the Deere E100 series and the Poulan/Husqvarna mowers to choose from. Good luck with your purchase.
Mike