There are not a lot of units that are more pocket friendly that use removable batteries.
Sigelei's/Vamo's/SVD's and others are actually "longer" than an MVP.
You can get some of these that are telescoping or have mini configurations that use an 18350, but your battery life is severely curtailed and you will need to carry spare batteries with you if you are going to be out an about more than a couple of hours.
The Coolfire I by Innokin is an 8.5 Watt regulated 18350 mod that looks pretty nice. It is regulated, so you won't get the voltage lag over the battery discharge profile like you would with a non-regulated battery or mechanical mod. But it's limited to 8.5 watts period. The Coolfire II is variable wattage, but looks like a grenade.
Another route is a mechanical with a Kick II. This provides wattage regulation, but the smallest format you will get with a kick is an 18350 with a kick which is the size equivalent to an 18500 battery.
Choices, choices....but before you look see what the minimum battery life you are interested in and move from there.
I personally like the VV3. It is much smaller and pocketable. It has the same capabilities of the MVP just lower capacity. It charges off USB just like the VV3. In fact some MVP2 users use the MVP2 to "charge" their VV3. So they keep their MVP2 in the car or purse and charge the VV3 off of it, and then when they leave the car, they have a fully charged VV3. (A fully charged MVP2 should be able to fully charge a VV3 at least twice and closer to 3 times....)
You should really determine what your minimum battery life is, then you can determine which "battery size" will fit those requirements in and then tailor your purchase around those devices.
