I've never used an XLT so I can't compare it to any other machine. I do own a V3i though and I believe it is still one of the best machines currently available. It isn't all peaches and cream though - it is a heavier machine (well balanced though) and it is NOT waterproof. Three frequencies at once, or select a single frequency of your choice. Best screen on the market and extremely user customizable - to the point that too many incorrect adjustments can really hamper performance. The stock programs are fine to start out with (turn on and go) and can be adjusted (for better performance) as you learn the machine. Good selection of coil choices. Great coin and jewelry machine.
No word, from Whites, on replacement plans (for the V3i).
Other machines you might wish to consider:
Whites MX Sport - waterproof single frequency machine. Very sensitive and deep. Great coin and jewelry machine. Not the best choice for salt water hunting, but it will do if salt water hunting is only an occasional thing (you'll lose some depth in salt water, but it will find good targets). Underrated machine in my opinion.
MX7 - basically the same machine as the MX Sport, but not waterproof (it is water/dust resistant). It is a bit less weight than the Sport - and a bit less costly.
Nokta/Makro Multi Kruzer or Multi Anfibio - both are multi frequency machines (single frequency at a time) and waterproof. I don't own the Anfibio so can't comment on it. The Kruzer is fast and deep. Very sensitive. Decent in salt water, but not the best choice if you're going to do a lot of salt water hunting. Deeper modes are … um sparky; as in they can be a bit too much in really trashy areas. The 7 inch concentric coil is fantastic (I much prefer it over the stock coil - which is a good coil itself). The Kruzer weighs less than either of the two Whites machines (V3i, MX Sport). The Kruzer is a great coin/jewelry machine.
Nokta/Makro Simplex - inexpensive, single frequency, waterproof machine. I haven't used one, but the reviews are very good.
Unless you're in a big hurry to get hunting right away, it might behoove you to hold off (on a machine) until spring. By then there will be another option to consider.