If you have to choose one, the 500 is most likely the one that will be the most useful to you unless you will be making very large projects. think it also is a great tool just like the DF500. I recently acquired the 700XL and, from my limited use of it so far. It is one of the most innovative and useful tools I own. I have owned the DF500 for about 2 years and it is a favorite tool in my shop. For the kind of work I do, investing in the 500 hasn't made sense to date. I haven't used the new connectors, nor have I compared it to the 500. Most pieces I've done incorporate around 100 dominoes, so the 700 gets a lot of use. The domino is perfect for hiding the joinery, while speeding up the job, and being strong enough to stand up to daily abuse. My furniture is a modern style that is more square with the beauty of highly figured wood grain being the star.

Picture frames are where the 500 would be better suited, but I do use the Seneca adaptor to get a 5mm cutter onto thinner stock.

I only have a 700XL and use it to build office furniture, many varying home projects, and picture frames.

With that 'lurker statement' out of the way let me respond to your request. Either way, the 700 will never cut shorter than 15mm (although the 500 is only 3mm shorter) and the 500 won't cut 70mm deep. You can always double or quadruple tenons with the 500 and you can get a Seneca cutter adaptor for the 700 to make either one more adaptable to varying projects. It all depends on the size of your projects.

Instaling XXL Picture Frame cs go skin