You were misinformed, Moons,

I love the EDP but it has the capability of
playing 16 loops but only sequentially.

It does not have multi-loop capacity.

So, far, the EDP is the most sophisticated hardware looper at slicing and dicing and manipulating the loop.
The software is amazing in this unit and I wouldn't dream of doing an experimental show without it.

That being said and done, it has an archaic processor (apple 2C), is only mono and doesn't allow
simultaneous loops (unless you run two of them or are performing with another musician who has one).
It also has a beautiful proprietary sycing system (as well as a midi sync to) that allows to units
to sync up. It's called Brother Sync and will allow kinds of syncing that are more sophisticated than
midi.

Additionally, you can use midi sync programs to automate the switcing between loops.
Andre LaFosse is one of the gods of this technique (also joined by the wonderful Swiss looper, Claude Voit).

If you want multiple loops in a hardware box, there are only two options:

the Electrix Repeater which is out of print but shows up on E-bay occasionally

and the new
Looperlative which has an amazing 8 full stereo tracks (16 in mono if you route it correctly to a mixer)
which you can either syncrhonize internally or not> You have the ability to run synchronous loops at the same time
that you have asynchronous loops and there are tons of options for using group fades and other group functioning
including some retuning of the samples. The retuning, however, does not have the stretching algorithms of programs
like ACID and Ableton's Live (the Repeater does do this and quite elegantly).

Additionally, there is an ether net port on the back of the unit that allows you to instantaneously download
software revisions which are free for the life of the unit. Bob Amstadt is continually creating new software at the behest
of the community of Looperlative owners. This means every owner is, ostensibly, a member of the R&D team.
If a software idea has enough demand amongst owners, Bob will write it in and , VOILA you'll have it in your machine.

I don't think any hardware device has ever had this amazing ability to upgrade so quickly.
Additionally, you can either load loops from a computer or store loops on a computer.

The unit has a whopping 500 mgz processor dedicated only to running the unit. They are fantastic but
the price is about $500 more than an ECHOPLEX.

I, myself, use the Repeater for tuning lops, the EDP for slicing and dicing and the Looperlative for
multi track looping and synchronization.

I'll be at the January NAMM show demonstrating the Looperlative with my brother, Bill Walker and british bassist, Steve Lawson
(all very experienced multi track looping artists) if you get down to the show.

Additionally, I live in Santa Cruz, if you ever want a demonstration of the unit.

The edp's my main, and usually only, looper.

As has been mentioned here, you can only run the loops one at a time.
That doesn't mean it's incapable of creating complex multitrack arrangements though,
as you can seemlessly copy from one loop to another while overdubbing.
Say you want to set up a rhythm, then want to overdub a longer melody, in that case the edp is easily the easiest looper to do that with, you don't even have to know how many bars the melody is.

Really, though, it's impossible to advise you without knowing your requirements.
There isn't a "best buy" looper, or an obvious upgrade path to follow.

If you say what you want to achieve ( that you can't do with your current device) then there'll be plenty of good advice here, and at www.loopers-delight.com