Despite the fact that eMobile was bought out my Softbank not long ago, the stores and brands are still operated separately - along with the networks.  This will probably change over time, but even if eMobile customers gain free roaming onto Softbank's networks, it doesn't mean that the current eMobile terminals will support it.

Since the GL01P was the first LTE model of Pocket WiFi, let's take a look at what's changed since then:

First of all, the main "feature" of the GL06P over the GL01P (and in fact the GL04P, etc. too) is that it's smaller. by quite a bit - depending on your definition of "smaller".  In fact, it's slightly thicker, but the "face" is smaller, so the general impression is that the device is smaller - and it now actually fits into normal pockets more easily.  It looks a bit sexier too, and they managed to do this while increasing the battery capacity by over 18%.  The SIM card has also gone from normal size to micro size.

The battery was increased by over 18%, yet the increased runtime is much more than that (over 33%), so they must have tweaked the electronics to increase efficiency a bit too.  

You might think "9 hours is a long time already...", and it is, but... it isn't.  

Let's take a look at a (supposedly) typical person's schedule:

08:00 Wake up

09:00 Leave House

10:00 Arrive at work

19:00 Leave work

20:00 Arrive at home

If you left the house at 9 and don't get back until 20:00, that's 11 hours.  It's true that maybe you could charge your Pocket WiFi at work, but it's also possible that you might not get home until 11pm, or 4am.  You might not be at work either, but at a theme park all day long.  

If you think of the Pocket WiFi as something you switch on, use for an hour or two while working, and then switch off, then perhaps even 2 hours is fine.  If you think of it as something to use with your computer, your mobile phone, your iPad, etc., then you probably want to leave it on continuously, and 9 hours becomes a very short amount of time.

One interesting thing to note is that when using 3G, the GL06P is only rated for 11 hours of continuous usage.  Clearly they concentrated on the LTE circuitry.  

The NAS feature that the GP02 had still hasn't made a comeback, but it wasn't very useful anyway, since [unlike a real NAS] it required using a web browser to access it every time.  Likewise, there is no SD card support.  

The GL01P launched with no USB networking support, and then added some semi-support which required a special network manager program and worked only in Windows.  The GL06P supports standards compliant USB networking out of the box.  This means that if you include the USB network, the GL06P can support 11 devices.  (Clearly you could share the network from your computer if you needed more).

The Multi-SSD feature from the GP02 has re-appeared, allowing you to create multiple networks with one router.  This could be useful to create a "guest network" for your friends.

Most interestingly, there is a new option buried deep in the settings, which allows the router to connect to WiFi.  At first, I was very confused by this, thinking "of course it connects via WiFi".  This setting is for the WAN side of the connection though, and allows the router to connect to a WiFi access point instead of 3G or LTE.  In other words, your router could connect to WiFi access points outside, or even the one in your house.  Why would you want to do that?  Speed, of course.  (And perhaps cost, if you were on a metered plan).  

Of course, you could just connect your computer or tablet or whatever directly to the wired network, negating the need for the Pocket WiFi at all - but the feature makes sense in the context of WiFi access point infrastructure run by the internet companies.  If you are in a location where there is WiFi, the unit can just switch to it automatically, and whatever you have connected to the PocketWiFi doesn't need to know or be configured.

As an aside, the Multi-SSD and WiFi WAN features can not be used simultaneously (Presumably they use the same hardware).

Lastly, the GL06P is LTE Category 4 enabled.  This means greater upload/download speeds than the GL01P in theory.  Theory indeed, because eMobile hasn't installed category 4 routers yet.