Full boil volume mashing

[inspiron23]

Hi, I’ve been brewing for about 5 years, all of those all grain, and have a question about mash volumes and how it would affect the beer.
I have a 2 kettle system, I mash in one kettle, and pump my wort into the boil kettle for boiling.

My current mash ratio is about 1.9L/lb.
I would like to simplify things and if possible do a full boil volume mash, or possibly, just top off my boil kettle with water to hit my volume after draining my wort off my grain bed.
If I did full boil volume mashing it would be around 3.0L/lb.
Is there any reason this can’t work? What problems could I run into? Sorry if I don’t have enough info here, any questions, ask away.

 

[CTS]

This is what I do as I have a 2 vessel system, mash with 9g of water at mash temp with a recirculating pump. Works great but you might have a bit lower efficiency and a higher mashing PH with this method.

 

[Yooper]

The only downside would be if you were using alkaline water and the mash pH was too high, but otherwise it would be fine.