upgrade to Marcum M1 or just get a lithium shuttle

I have a marcum vx-1p flasher that I use. Is it worth the extra money to upgrade to the m1 or m3, or just get the lithium shuttle for my current model?

Personally if you’re in the market to upgrade, I’d just go with a M3 with a lithium shuttle. It’s $150 more than a “standard” and it has the USB plugs and lights.
But if your happy with a VX-1p upgrade to the lithium.

Upgrade as in getting a spare as backup.

I’d have to agree with everyone so far. Personally I’d do the upgrade also. All 3 of those systems are easy to figure out and run. The major difference is the M3 has the adjustable zoom throughout the entire water column and is a little more powerful if that makes a difference to you. Don’t think you can go wrong with it but if the budget permits I’d look into getting the shuttle with it. Getting my hands on one soon great accessory.