Only you can really answer this question, but if while you were using your Domino you used the largest tenons most often then it might be a good idea hat enhances your future work.

Peter

Get an XL and try it for 30 days before selling the DF 500.

I have been using the 500 for a year now, and the 700 for about 7 months. The area where they overlap is smaller than you might think.
In fact i have never asked myself which one i should use for the task, it comes naturally. I always give priority to the 500 because of the size and weight, and i still use it for the  same tasks i did before. The XL is made for different work, and in my case it doesn't take any of the 500's work over.

That being said, if you almost exclusively use the 8 or 10mm dominos with your 500 already, then the XL could in theory take over.
Nothing stops you from keeping the 500 while getting the 700, and making a decision after. it could become an expensive error if you find out later that you do need a 500 after all.

Putting my $.02 in on this - they're two tools designed to do the same task, but at different levels. I equate it to a Football (American) team having two running backs - one for the majority of the work, and another larger stronger back for pounding away at yardage.....

my way of thinking is if the 500 has been working for ya then keep it.

I have a project coming up where a 700 would be ideal.

But b/c its only one project Im not going to buy one.

Im going to make the 500 work.

Its all personal preference.

You wont have a hard time selling yer domino.

It will go fast.

but remember , once its gone its gone.

I still wish my Jets kept little Leon Washington, but I'll stay on topic....everyone has made great points. I guess it depends on what end of the spectrum of work Evergreen does. One Domino is certainly not better than the other - just two different capacities.

Lot's of good responses!  Thanks for all the input!  I make a lot of custom door's of all sorts: Screen doors, french door's, exterior gates, carriage, etc..., as well as built ins, etc...   Therefore it would make sense to own the XL.  The only reason I ask the question is, I'm not sure I can swallow spending $1200 on another domino at this time.  Obviously if I sold the 500 it would greatly help to fund a tool that I most likely would use more than my current domino, but at the same time don't want to regret it in the end.  I think I will purchase the XL and from there get a sense if I need both or if one will do.  In the end, I'm guessing I'll need to find a new spot in my trailer for another domino;)

Six weeks.....

The 8mm is pushing it a bit for use in the edge of 3/4", depending of course on the type of material and application. If you have used that  with out problems then no biggie, but something to consider.

Seth

I understand wanting the newest cool gadget to hit the streets.  This one is a specialty tool that few people will actually use for more than one or two projects.  There's nothing wrong with spending the money if you have it.....however, if anyone is on the fence, you probably don't need one.  Evergreen just might be the exception. 

With all of the impulse buys, there are going to be a lot XL's sitting on garage shelves unused here in N. America in the near future.  Wait a year or so and number of "like new" XL's will be hitting the classified section.

If you can justify it keep both.  For the type of doors you are describing then you definitely need the XL.  I am doing an Ash door just now with the XL & it is such a time saver.
When I first heard Festool were releasing a bigger Domino I thought to myself, what a stupid idea but I can tell you I had one pretty soon after realeased & not regretted it for a second.  The first 2 jobs I did with it it paid for itself in the saved time !