x-treme ebike owners/riders?

http://www.x-tremescooters.com/electric_bicycles/xb300sla/xb300sla.html

While I've no direct experience with that particular model & you may well be aware of all of this, as a bit of an ebike enthusiast I can safely say that you would be astounded should you no more then upgrade the "2 Large SLA Batteries" to a LifePO4 pack. It's both awkward & somewhat revealing that they don't specify the AH (amp hours/reserve) or weight of the stock SLA pack, this is unfortunately a not uncommon practice with SLA ebike retailers, likely for the following reasons;

A basic replacement 24V 10AH LifePO4 pack (guestimate for your bike) may seem spendy at $200 or so, but weighs a mere 5lbs, is about half the size of equivalent lead-acid batteries, the weight about a third & the total life cycle about 2000 - which is roughly 6-7 times longer than SLA. LifePO4 also has no "memory effect" so partial charge/discharge is not a concern & they still preform well in colder temperatures, unlike SLAs.

LifePO4 also isn't subject to the potential thermal runaway of it's lithium predecessors, while sightly more costly w/a touch less reserve then it's lithium-ion equivalent, you can safely ignore any "reports of exploding cellphones" lol

As you are generally "impressed with the quality of the bike" yet concerned about "long term experience" I'd suggest the batteries the only area for improvement, they are after all the absolute most critical aspect of any electric vehicle, the number one cause for satisfaction & dissatisfaction both

I have seen those on ebay and they look like good bikes to me. Very easy to upgrade to 48v li-ion for a nice performance boost.

Funny when I looked at the title of this thread I thought it would be about a high voltage super amped bike-lol!

Looks like a nice bike! You have gotten good advice on the battery upgrades, something well worth considering especially if hills factor in.
However I built my wife a cruiser using a 36v 250w hub and set it up with SLAs to avoid any issues of it handling the abuse she usually imposes on stuff. Like I came in the other day and the system was still on(couple of days) and the batteries were really low. Not a good scenario for some of the other battery chemistries. SLAs of course took it in stride.
All of my bikes have either Li-Ion or Lipo systems. I like these chemistries. The Lifepo4 is probably the best all around due to its somewhat forgiving characteristics.
Im with Kevyleven, Id run out the SLAs then swap out the controller and over volt the motor to either 36 or 48v(36 probably as the batteries are cheaper). I would use the dastardly much feared Lipo chemistry for a very light weight little speedster!(not advising you to do this, I gotta lot of hands on with it). At any rate looks like you got a cool little bike. Have fun with it!

heres the stepthru version and the price is not bad http://www.ebay.com/itm/XB-305SLA-S...m-/261612817430?ssPageName=ADME:SS:SS:US:3160 and a folding lithium one here http://www.ebay.com/itm/X-Treme-XB-...=100011&prg=10672&rk=2&rkt=10&sd=291257123227 I don't think you could have found a better new ebike for less money ( just my opinion).