Yes I know, in fact I use Boltz to swap from lightning to liquid, always with very low fees.
Instead from lightning to on-chain the swap on Boltz is affected by the normal fees of the market at that time
Discussion
It’s true, but by having your sats in Liquid, you’re trusting the Blockstream federation to peg out your L-BTC when you ask for it. If it’s fine with you, then nothing speaks against that. If you prefer to have real on-chain bitcoin in a hardware storage, you will need to pay the fees sooner or later. Luckily, they’re relatively low now.